>>> TONIGHT, THE NEW RACE FOR THE WHITE HOUSE HEATING UP AS KAMALA HARRIS SAYS SHE'S READY TO DEBATE DONALD TRUMP. THE VICE PRESIDENT ACCUSING MR. TRUMP OF BACKPEDALING FROM HIS COMMITMENT TO DEBATE IN SEPTEMBER. THE FORMER PRESIDENT GOING ON THE ATTACK, CALLING HARRIS A RADICAL AND VOWING, QUOTE, I'M NOT GOING TO BE NICE. AND THE BRAND-NEW POLLING. HOW DO HARRIS AND TRUMP MATCH UP? >>> ALSO TONIGHT, ISRAELI PRIME MINISTER BENJAMIN NETANYAHU AT THE WHITE HOUSE, A DAY AFTER HIS FIERY ADDRESS TO CONGRESS. PRESIDENT BIDEN PUSHING HIM TO ACCEPT A CEASEFIRE IN GAZA, AND HIS SEPARATE MEETING WITH KAMALA HARRIS. THE VICE PRESIDENT TODAY CONDEMNING PROTESTS DURING NETANYAHU'S SPEECH AS DESPICABLE. >>> THE RAGING WILDFIRE IN NORTHERN CALIFORNIA EXPLODING TO 71,000 ACRES IN LESS THAN 24 HOURS. MULTIPLE HOMES DESTROYED. EMERGENCY EVACUATIONS ORDERED, AND NOW WORD OF AN ARREST FOR STARTING THAT INFERNO. >>> SOUTHWEST AIRLINES, FAMOUS FOR ITS OPEN SEATING, ANNOUNCING ITS BIGGEST CHANGE IN MORE THAN 50 YEARS. >>> THE BOEING STARLINER. ASTRONAUTS NOW ON DAY 50 OF WHAT WAS SUPPOSED TO BE A TEN-DAY MISSION. AND NASA CONFIRMING TODAY STILL NO RETURN DATE. >>> AND THE FINAL COUNTDOWN HERE IN PARIS. JUST ONE DAY UNTIL THE 2024 OLYMPICS OPENING CEREMONY THAT PROMISES TO BE UNLIKE ANYTHING YOU'VE S >> Announcer: THIS IS "NBC NIGHTLY NEWS," REPORTING TONIGHT FROM THE OLYMPICS IN PARIS. HERE IS LESTER HOLT. >> AND GOOD EVENING TONIGHT FROM PARIS. I'M TOM LLAMAS IN FOR LESTER. AS THIS CITY GETS READY FOR THE WORLD TO FOCUS ON THE OLYMPICS WITH THE OPENING CEREMONY LESS THAN 24 HARRIS AWAY, IN THE U.S., THE SPRINT TO NOVEMBER IS ON. VICE PRESIDENT HARRIS TELLING FORMER PRESIDENT DONALD TRUMP SHE WANTS A DEBATE, SAYING "I'M READY. LET'S GO." FORMER PRESIDENT TRUMP SAYING HE WON'T BE NICE AND PAINTING HER AS A RADICAL LIBERAL. JOINING THE FRAY, BEYONCE, OR AT LEAST HER MUSIC, AND FORMER PRESIDENT OBAMA, SET TO ENDORSE. ALL OF IT COMING AFTER PRESIDENT BIDEN'S HISTORIC OVAL OFFICE ADDRESS, SAYING HIS DECISION NOT TO RUN IS ABOUT THE VERY FUTURE OF DEMOCRACY. IT'S WHERE WE START TONIGHT WITH CHIEF WHITE HOUSE CORRESPONDENT PETER ALEXANDER. >> Reporter: TONIGHT, VICE PRESIDENT HARRIS WELCOMING AN ONSTAGE SHOWDOWN WITH FORMER PRESIDENT TRUMP, ACCUSING HIM OF BACKPEDALING FROM HIS PREVIOUS COMMENT TO A SEPTEMBER DEBATE. >> I'M READY TO DEBATE DONALD TRUMP. I THINK THE VOTERS DESERVE TO SEE THE SPLIT SCREEN THAT EXISTS IN THIS RACE ON A DEBATE STAGE. AND SO I'M READY. LET'S GO. >> Reporter: JUST THIS WEEK, MR. TRUMP SAID HE'D BE WILLING TO DO MORE THAN ONE DEBATE WITH MS. HARRIS, BUT APPEARED TO BALK AT THE CURRENT PLAN. >> I AGREED TO A DEBATE WITH JOE BIDEN. BUT I WANT TO DEBATE HERE. IT STILL BE NO DIFFERENT, BECAUSE THEY HAVE THE SAME POLICIES. >> Reporter: THEIR HEAD-TO-HEAD IS QUICKLY HEATING UP. NEW POLLING SHOWS THE VICE PRESIDENT HAS NARROWED MR. TRUMP'S ADVANTAGE OVER PRESIDENT BIDEN, THE RACE EFFECTIVELY A TOSS-UP. ON THE ECONOMY, HARRIS TODAY SLAMMING THE FORMER PRESIDENT'S PROPOSALS AS TAX BREAKS FOR BILLIONAIRES. >> AMERICA HAS TRIED THESE FAILED ECONOMIC POLICIES BEFORE. BUT WE ARE NOT GOING BACK. WE ARE NOT GOING BACK. >> Reporter: MR. TRUMP TODAY ATTACKING THE VICE PRESIDENT. >> SHE'S THE MOST RADICAL PERSON PROBABLY THAT WE'VE HAD IN OFFICE, LET ALONE THE OFFICE OF THE PRESIDENCY. >> Reporter: IN CHARLOTTE LAST NIGHT CASTING ASIDE HIS PROMISE FROM LAST WEEK'S REPUBLICAN CONVENTION THAT HE'D STRIKE A MORE UNIFYING TONE. >> HE CAN'T BE TOO NICE. HE REALLY CAN'T BE. IF YOU DON'T MIND, I'M NOT GOING TO BE NICE. IS THAT OKAY? >> Reporter: IT COMES AS PRESIDENT BIDEN DETAILED HIS DECISION TO DROP OUT OF THE RACE. >> I REVERE THIS OFFICE, BUT I LOVE MY COUNTRY MORE. >> Reporter: DISCUSSING HIS DESIRE TO UNITE THE COUNTRY BY PASSING THE TORCH TO A NEW GENERATION. >> THERE IS ALSO A TIME AND A PLACE FOR NEW VOICES, FRESH VOICES, YES, YOUNGER VOICES. AND THAT TIME AND PLACE IS NOW. >> Reporter: THE VICE PRESIDENT SOON TO RECEIVE A MAJOR BOOST. THE ENDORSEMENT OF FORMER PRESIDENT OBAMA, ACCORDING TO PEOPLE FAMILIAR WITH THEIR DISCUSSIONS WHO SAY THE TWO HAVE BEEN IN CLOSE TOUCH SINCE SHE ANNOUNCED HER PLANS TO RUN. >> IN THIS ELECTION, WE EACH FACE A QUESTION. >> Reporter: THE HARRIS TEAM NOW RUNNING WITH ITS FIRST CAMPAIGN VIDEO. ♪ FREEDOM, FREEDOM, I CAN'T MOVE ♪ >> Reporter: SET TO THE BEYONCE SONG "FREEDOM." MEANWHILE, MR. TRUMP'S RUNNING MATE J.D. VANCE IS FACING NEW BACKLASH FOR HIS PAST CRITICISM OF DEMOCRATIC LEADERS, INCLUDING MS. HARRIS, FOR NOT HAVING CHILDREN. >> WE'RE EFFECTUALLY RUNNING THIS COUNTRY VIA THE DEMOCRATS, VIA OUR CORPORATE OLIGARCHS BY A BUNCH OF CHILDLESS CAT LADIES. >> Reporter: HOLLYWOOD STAR JENNIFER ANISTON POSTING, "ALL I CAN SAY, MR. VANCE, I PRAY THAT YOUR DAUGHTER IS FORTUNATE ENOUGH TO BEAR CHILDREN OF HER OWN ONE DAY." AND KRISTEN EMHOFF PRAISING AS A COPARENT TO THE CHILDREN. I LOVE OUR BLENDED FAMILY AND AM GRATEFUL TO HAVE HER IN IT. AND PETER, WE ARE IN THE VERY EARLY DAYS OF THE HARRIS CAMPAIGN. BUT THEY'RE ALREADY EMBRACING A DIFFERENT APPROACH. >> Reporter: YEAH, I THINK THAT'S RIGHT, TOM. I THINK IN BOTH STYLE AND STRATEGY. STYLISTICALLY, THE VICE PRESIDENT IS EMBRACING POP CULTURE, MEMES, AND APPEALING TO YOUNGER VOTERS WHO HAVE BEEN LESS THAN ENTHUSIASTIC ABOUT PRESIDENT BIDEN, BUT ALSO PERHAPS STRATEGICALLY A DIFFERENT ELECTORAL MAP. THE HARRIS CAMPAIGN NOW HOPING THAT HER CANDIDACY WILL MOBILIZE DIFFERENT DEMOGRAPHICS, INCLUDING SOUTHERN BLACK VOTERS IN STATES LIKE GEORGIA WHERE VICE PRESIDENT HARRIS WILL HEAD EARLY NEXT WEEK. TOM? >> THE NEW RACE IS DEFINITELY UNDER WAY. ALL RIGHT, PETER, WE THANK YOU FOR THAT. >>> NOW TO THE HIGH-STAKES MEETING THAT HAPPENED RIGHT THERE AT THE WHITE HOUSE. WITH THE FUTURE OF THE WAR IN GAZA AND THE LIVES OF THE HOSTAGES HELD BY HAMAS IN THE BALANCE, PRESIDENT BIDEN AND VICE PRESIDENT HARRIS PUSHING ISRAELI PRIME MINISTER BENJAMIN NETANYAHU TO REACH A PEACE DEAL. HERE IS ANDREA MITCHELL. >> PRESIDENT BIDEN AND ISRAEL PRIME MINISTER BENJAMIN NETANYAHU HAD THEIR FIRST MEETING SINCE THE EARLY DAYS OF THE WAR. >> WELL, WELCOME BACK, MR. PRIME MINISTER. WE'VE GOT A LOT TO TALK ABOUT. >> Reporter: WITH TIME NOW RUNNING OUT TO CLOSE A CEASEFIRE AND HOSTAGE DEAL BEFORE HE LEAVES OFFICE, MR. BIDEN PRESSING THE ISRAELI LEADER ON A CEASEFIRE. >> IT'S TIME NOW TO GET THE NEGOTIATION IN PLACE AND GET THE HOSTAGES HOME. IT'S TIME TO END THE WAR. >> SHAME, SHAME, SHAME ON YOU! >> Reporter: NETANYAHU'S VISIT SPARKING DAYS OF OUTRAGE. TODAY PROTESTERS RALLYING NEAR THE WHITE HOUSE. YESTERDAY, POLICE USED PEPPER SPRAY AS HUNDREDS DEMONSTRATED AROUND THE CAPITOL. PAINTED PRO HAMAS AND ANTISEMITIC GRAFFITI, BURNED AN AMERICAN FLAG AND RAISED PALESTINIAN FLAGS, ACTIONS STRONGLY CONDEMNED BY CONGRESSIONAL LEADERS IN BOTH PARTIES AND BY VICE PRESIDENT KAMALA HARRIS. TODAY THE WHITE HOUSE ALSO PUTTING NETANYAHU ON THE SPOT BY INVITING AMERICAN HOSTAGE FAMILIES TO MEET WITH HIM AND THE PRESIDENT IN THE CABINET ROOM. >> WE GOT ABSOLUTE COMMITMENT FROM THE BIDEN ADMINISTRATION AND FROM PRIME MINISTER NETANYAHU THAT THEY UNDERSTAND THE URGENCY OF THIS MOMENT NOW. >> Reporter: AVIVA SIEGEL, HER AMERICAN HUSBAND KEITH A HOSTAGE. SHE WAS RELEASED AFTER 51 DAYS, BUT SAW THE HORRORS FIRSTHAND. >> I WANT EVERYBODY JUST TO IMAGINE ANY GIRL THAT'S A YOUNG GIRL THAT'S NEVER BEEN TOUCHED. SHE'S LYING ON A MATTRESS ON THE FLOOR AND JUST PRAYING, PLEASE, JUST THAT HE WON'T TELL ME TO COME THIS TIME AND DO WHAT HE DID YESTERDAY. I'M VERY, VERY WORRIED. I DO NOT WANT KEITH TO COME BACK DEAD. AND I WANT ALL THE HOSTAGES TO COME BACK AS SOON AS POSSIBLE, BECAUSE WE HEAR ABOUT MORE AND MORE OF THEM THAT ARE KILLED. >> Reporter: EVEN AS THE IDF RECOVERED FIVE MORE BODIES OF ISRAELI HOSTAGES FROM A TUNNEL IN KHAN YOUNIS, WHO HAD BEEN KILLED ON OCTOBER 7th. AND LATE TODAY VICE PRESIDENT HARRIS AND NETANYAHU IN THEIR FIRST MEETING SINCE BIDEN DROPPED OUT OF THE 2024 RACE. HARRIS DECLINED TO PRESIDE OVER NETANYAHU'S SPEECH TO CONGRESS. DONALD TRUMP'S RUNNING MATE, SENATOR J.D. VANCE ALSO NOT THERE. >> I ALSO EXPRESSED WITH THE PRIME MINISTER MY SERIOUS CONCERN ABOUT THE SCALE OF HUMAN SUFFERING IN GAZA, INCLUDING THE DEATH OF FAR TOO MANY INNOCENT CIVILIANS. >> Reporter: TOMORROW NETANYAHU FLIES TO MAR-A-LAGO TO SEE FORMER PRESIDENT TRUMP, WHO SAID TODAY HE WANTS HIM TO GET THE WAR DONE QUICKLY. TOM? >> ALL RIGHT, ANDREA. WE THANK YOU FOR THAT. >>> NOW TO THE INTENSE FIREFIGHT TONIGHT IN NORTHERN CALIFORNIA, WHERE THEY'RE BATTLING A FAST-SPREADING AND DESTRUCTIVE WILDFIRE THAT'S THE BIGGEST OF THE YEAR IN THE STATE. AN ARSON SUSPECT NOW UNDER ARREST. MORGAN CHESKY IS THERE. >> Reporter: TONIGHT, A WEST COAST FURNACE TURNED INFERNO. CALIFORNIA'S PARK FIRE EXPLODING OVERNIGHT, FORCING RESIDENTS TO EVACUATE IN CHICO, NORTH OF SACRAMENTO. THE HEAT IS INSANE. SPOT FIRES EVERYWHERE. >> Reporter: AND LESS THAN 24 HOURS, THE WIND-DRIVEN INFERNO SCORCHED MORE THAN 70,000 ACRES. ENTIRE HOMES AND BUILDINGS ENGULFED IN FLAMES THAT AUTHORITIES ARE NOW CALLING AN ACT OF ARSON, ARRESTING A 42-YEAR-OLD MAN FROM CHICO FOR PUSHING A FLAMING CAR INTO A RAVINE, WHICH THEY SAY STARTED THE FIRE. JUST OUTSIDE COHASSET, SMOLDERING DEBRIS IS ALL THAT REMAINS WHERE HOMES ONCE STOOD. IN BUTTE COUNTY, CREWS HAVE ALREADY MADE THEIR WAY BACK TO SEVERAL REMOTE AREAS, TRYING TO CUT FIRE LINE WHEREVER THEY CAN TO SLOW THE SPREAD. FROM CALIFORNIA TO CANADA, MONTHS WITHOUT RAIN AND RECORD HIGHS HAS TURNED MUCH OF THE WEST INTO A TINDERBOX. THE CAN DURKEE FIRE IN OREGON IS NOW THE NATION'S LARGEST, CHARRING NEARLY A QUARTER MILLION ACRES, IGNITING FROM A LIGHTNING STRIKE LAST WEEK. THE BLAZE SO BIG IT'S CREATING ITS OWN WEATHER, WITH EXTREME HEAT FORMING A FIRE-FUELED THUNDERSTORM, CARRYING SMOKE AND ASH EVEN FARTHER. AS CREWS FROM 22 STATES FIGHT 24/7 TO CONTAIN IT, A SIMILAR STRUGGLE IN ALBERTA, CANADA. THE PICTURESQUE TOWN OF JASPER NOW FACING NEAR APOCALYPTIC SCENES AS FLAMES CLOSE IN. THE FIRE SMOKE SO THICK, IT'S IMPACTED AIR QUALITY AS FAR SOUTH AS COLORADO, A GRAY HAZE HANGING HEAVY. BACK NEAR CHICO, WITH FLAMES FAR FROM CONTAINED, EVACUATION ORDERS REMAIN ONGOING. >> THE QUICKER YOU GET OUT, THE SAFER YOU WILL BE. >> Reporter: AND TONIGHT AS THIS FIRE VERY MUCH KEEPS BURNING, A FRIGHTENING DEJA VU. IT WAS SIX YEARS AGO THAT A WILDFIRE LEFT 85 PEOPLE DEAD AND DESTROYED NEARLY 90% OF THE TOWN OF PARADISE. SOME OF THOSE SURVIVORS RESETTLING IN NORTH CHICO IN AN AREA THAT TONIGHT IS FRIGHTENINGLY CLOSE TO THIS VERY FIRE. TOM? >> UNBELIEVABLE. ALL RIGHT, MORGAN CHESKY AND HIS TEAM NEAR THE FIRE LINE TONIGHT. >>> BACK HERE IN PARIS, WE ARE LESS THAN 24 HOURS UNTIL THE OPENING CEREMONY OF THE SUMMER OLYMPICS. THE CITY JUST BEHIND US HERE TRANSFORMED INTO A GRAND STAGE FOR THE ATHLETES AND A SECURITY FORTRESS. THE ATHLETES ARE HERE. THE CITY IS ABUZZ, AND THE COUNTDOWN IS ON TO WHAT MIGHT BE THE MOST AMBITIOUS OPENING CEREMONY EVER, THE FIRST HELD OUTSIDE OF A STADIUM. TOMORROW, MORE THAN 10,000 ATHLETES IN NEARLY 100 BOATS WILL FLOAT FOUR MILES DOWN THE SEINE. IN THE LEAD-UP TO THE OPENING CEREMONY, PARTS OF PARIS ARE TURNING INTO A SECURITY MAZE. BARRIERS, FENCES, 45,000 POLICE OFFICERS, 10,000 SOLDIERS, 20,000 PRIVATE SECURITY. SNIPERS ON ROOFTOPS. DIVERS IN THE WATER. FIRST LADY JILL BIDEN WILL BE THERE, LEADING THE U.S. DELEGATION. TODAY, ACTING AS TEAM USA'S CHEERLEADER IN CHIEF. >> WE ARE ALL FIRST AND FOREMOST TEAM USA. [ APPLAUSE ] >> SWANSON! >> Reporter: TEAM USA'S WOMEN'S SOCCER TEAM SAW THEIR FIRST OLYMPIC ACTION TODAY. THE YOUNG SQUAD SENDING A MESSAGE WITH A DECISIVE WIN OVER ZAMBIA. >> 27 SHOTS ON GOAL. >> Reporter: ARCHERY ALSO KICKING OFF, WITH A SOLID SHOWING FROM AMERICAN CASEY KAUFHOLD, RANKED NUMBER ONE IN THE WORLD. WHILE WE GOT A LOOK AT SIMONE BILES AND HER TEAMMATES AT WARM-UP, TRAINING TODAY, BILES WARMING UP HER FAMOUSLY DIFFICULT VAULT, THE YURCHENKO DOUBLE PIKE. >> OH MY GOD! >> Reporter: A PERSONALIZED OLYMPIC PIN FROM BILES HAS QUICKLY BECOME ONE OF PARIS' MOST SOUGHT AFTER ACCESSORIES, WHILE THE OLYMPIC VILLAGE IS THE PLACE TO BE. TODAY TEAM USA POSTING THIS PICTURE OF ITS YOUNGEST MEMBERS MEETINGS. GYMNAST HEZLY RIVERA AND SPRINTER QUINCY WILSON, BOTH ONLY 16. >> TO BE WITH THE OTHER ATHLETES THAT REPRESENT OUR COUNTRY AS WELL IN ALL THE DIFFERENT SPORTS AND EVENTS, THAT'S YOU REALLY GET JUICED. >> WE ARE LOOKING FORWARD TO IT ALL. >>> IN 60 SECONDS, THE BIG CHANGE IN THE AIR FOR SOUTHWEST AIRLINES. WHY IT'S DITCHING ITS TRADEMARK OPEN SEATING AND THE OTHER CHAN >>> IT IS NOW DAY >>> IT IS NOW DAY 50 OF WHAT WAS SUPPOSED TO BE A TEN-DAY MISSION FOR BOEING'S STARLINER. BUT THE TWO ASTRONAUTS ON THE CREW ARE NO LONGER CLOSER TO COMING HOME. NASA SAYING TODAY IT'S IDENTIFIED THE ISSUES THAT HAVE KEPT THE SPACECRAFT DOCKED AT THE INTERNATIONAL SPACE STATION FOR SEVEN WEEKS, BUT CONFIRMING THERE IS STILL NO RETURN DATE YET. >>> ALSO TONIGHT, CHANGES IN THE AIR FOR SOUTHWEST AIRLINES PASSENGERS. LONG KNOWN FOR ITS OPEN SEAT BOARDING POLICY, SOUTHWEST ANNOUNCING ITS BIGGEST CHANGES IN MORE THAN HALF A CENTURY. EMILIE IKEDA EXPLAINS WHY. >> Reporter: A MAJOR CHANGE OF COURSE FOR SOUTHWEST AIRLINES, ANNOUNCING TODAY IT WILL SOON START ASSIGNING SEATS AND SELLING SOME WITH EXTRA LEG ROOM, ENDING MORE THAN 50 YEARS OF ITS FAMOUS, OR FOR SOME INFAMOUS MODEL OF OPEN SEATING, WHERE BOARDING CAN BUILD INTO A MAD DASH. >> YOU GOT PEOPLE JUST RUNNING IN FRONT OF YOU. >> Reporter: AND WHILE SOME SOUTHWEST SUPER FANS ARE DISAPPOINTED. >> I LOVE OPEN SEATING. THAT'S WHY I FLY SOUTHWEST. >> Reporter: THE DISCOUNT CARRIER CEO SAYS THE MOVE IS A BID TO BOOST REVENUE AND ADAPT TO TRAVELERS' EVOLVING TASTES. REPORTING 80% OF SOUTHWEST CUSTOMERS WANT AN ASSIGNED SEAT, ESPECIALLY ON LONGER FLIGHTS. >> WHEN A CUSTOMER DEFECTS FROM SOUTHWEST TO ANOTHER COMPETITOR, IT'S THE NUMBER ONE REASON. SO IT'S THE RIGHT THING AT THE RIGHT TIME. >> Reporter: DESPITE THIS SUMMER'S RECORD TRAVEL, MANY AIRLINES ARE GRAPPLING WITH OVERCAPACITY. SOUTHWEST RECORDED A 46% DROP IN PROFIT FROM LAST YEAR, FACING GROWING RIVALRIES AND OTHER BUDGET OPTIONS. WHAT KIND OF HEADWIND IS THE AIRLINE FACING RIGHT NOW? >> THEY HAVE SIMPLY ADDED TOO MANY SEATS WHEN IT COMES TO BASIC ECONOMY SEATS. IN OTHER WORDS, THE SEATS THAT PEOPLE ARE BUYING AT THE LOWEST POSSIBLE FARE. SO MANY HAVE BEEN ADDED INTO THE SYSTEM, NOT JUST BY SOUTHWEST, BUT BY OTHER AIRLINES AS WELL, IT'S PUT A LID ON FARES. >> Reporter: SOUTHWEST SAYS BOOKINGS FOR ASSIGNED AND PREMIUM SEATS WILL BECOME AVAILABLE SOME TIME NEXT YEAR. THE CHANGE STILL REQUIRES UPDATING THE CABIN LAYOUT AND FAA APPROVAL. TOM? >> ALL RIGHT, EMILY, WE THANK YOU FOR THAT. >>> COMING UP, WE TAKE YOU ON A JOURNEY ALONG THE RIVER SEINE, THE LIFEBLOOD OF THIS CITY, AND NOW A STAR >>> AND WE ARE BACK NOW WITH THAT VIEW RIGHT THERE OF THE ALEXANDER III BRIDGE OVER THE RIVER SEINE HERE IN PARIS. TOMORROW, THAT FAMED RIVER THERE WILL HOST THE SPECTACULAR OPENING CEREMONY FOR THE OLYMPIC GAMES. IT'S ALSO THE CULTURAL LIFEBLOOD OF THE CITY. HERE IS KEIR SIMMONS. >> Reporter: IN PARIS TONIGHT, THERE ARE BLEACHERS ON THE BRIDGES AND TV SCREENS ON THE BANKS OF THE SEINE. MONTHS OF WORRIES OVER STRONG CURRENTS AND WATER QUALITY MOSTLY IN THE REAR VIEW MIRROR. AS THE RIVER BECOMES A STAGE FOR A HISTORY-MAKING OPENING CEREMONY FROM NOTRE DAME TO THE EIFFEL TOWER. THAT'S AS IT SHOULD BE, BECAUSE THE SEINE, ITS BANKS ADORNED WITH CAFES AND BOOK SELLERS IS OLDER THAN PARIS ITSELF. "THE SEINE IS PARIS" YOU EVEN SAY WHERE YOU ARE IN THE CITY IN RELATION TO THE RIVER. >> IT'S THE LEFT AND THE RIGHT BANK, NOT THE NORTH AND THE SOUTHBANK. IT'S BECAUSE THE RIVER TWISTS SO OFTEN. >> Reporter: AMERICAN HISTORIAN RUSSELL KELLY HAS LIVED HERE FOR 30 YEARS. >> THAT IS THE CENTER OF PARIS. >> Reporter: AND SAYS PARIS BEGAN ON AN ISLAND ON THE SEINE, THE ILE DE LA CITE, NOW KNOWN FOR ITS FAMOUS CATHEDRAL. WE FOLLOWED THE RIVER THROUGH PICTURESQUE VILLAGES FOR THREE HOURS TO ITS SOURCE. >> WELCOME. >> BONJOUR. >> THANK YOU. >> WELCOME. >> THIS IS THE FIRST BRIDGE? >> THE FIRST BRIDGE OF THE SEINE. >> AND RIGHT BANK AND LEFT BANK? >> Reporter: ANTOINE IS FROM FRIENDS OF SOURCE-SEINE AND SPENT HIS CHILDHOOD HERE. >> IT'S A MAGICAL RIVER. >> Reporter: THE GAULS AND THE ROMANS REVERED THIS PLACE. IN THE 19th CENTURY THEY BUILT A SHRINE. OH, YES YOU SEE THE WATER. THAT'S THE SOURCE RIGHT THERE? >> THAT'S THE SOURCE. >> Reporter: WHETHER THE SEINE IS CLEAN ENOUGH FOR OLYMPIC SWIMMING HAS BEEN HOTLY DEBATED. AND UP HERE AT THE SOURCE, IT'S SAFE TO TAKE A SIP. IT'S FRESH. >> IT'S CLEAN. >> YES. >> KEIR SIMMONS, GLAD YOU'RE WITH US AFTER DRINKING THAT RIVER WATER. >> TOUGH ASSIGNMENT. >> SO YOU TOOK THE JOURNEY. WHAT DID YOU LEARN? >> YOU KNOW, PARISIENNES BUILD THEIR LIVES AROUND THE SEINE. THAT VILLAGE 60 MILES SO FAR AWAY, IT MEANS SO MUCH TO THEM, THAT VILLAGE IS OFFICIALLY A DISTRICT OF PARIS. >> WE APPRECIATE THAT GREAT STORY HERE. >>> UP NEXT, THE LONG ROAD FROM UKRAINE TO PARIS. HOW TWO TOP ATHLETES >>> AND WELCOME BACK FROM PARIS, AND A LOOK AT THE EIFFEL TOWER AND THE LIGHT SHOW ILLUMINATING IT. >>> FINALLY TONIGHT, AMONG THE ELITE ATHLETES GATHERED HERE, SEVERAL FROM UKRAINE HAVE MADE THE HARD JOURNEY TO COMPETE FOR SOMETHING EVEN BIGGER THAN THE GAMES. HERE IS RICHARD ENGEL. >> Reporter: WHEN RUSSIA INVADED UKRAINE IN FEBRUARY 2022, BOGDAN YANOV, A JUDOON WAS T FOR PARIS. >> 5:00 IN THE MORNING, MY BEST FRIEND CALL ME AND SAY IT STARTED. >> Reporter: SO WAS YAROSLAVA MAHUCHIKH, THE WORLD'S NUMBER ONE-RANKED HIGH JUMPER. >> I FELT FEAR INSIDE, AND I SAY GOODBYE TO MY LIFE. >> Reporter: WITH TRAINING FACILITIES TORN APART BY RUSSIAN BOMBS -- BELIEVE IT OR NOT, IT WAS A NICE GYMNASIUM HERE -- AND CONSTANT AIR RAID SIRENS INTERRUPTING ALMOST EVERY PRACTICE -- >> IF START ATTACK, WE HAVE A BOMB SHELTER IN OUR SPORT HALL. >> Reporter: SUDDENLY, THE TWO ATHLETES FACED AN IMPOSSIBLE CHOICE. SHOULD THEY GO ABROAD WHERE IT'S SAFER OR REMAIN IN UKRAINE? BOGDAN CHOSE TO STAY. HE COULDN'T BEAR TO LEAVE HIS WIFE AND SON. >> SOMETIMES IT'S REALLY HARD TO FIGHT. BUT I WANT TO WIN FOR MY COUNTRY AND MAKE OUR PEOPLE A LITTLE BIT HAPPY. >> Reporter: YAROSLAVA MADE THE PAINFUL DECISION TO GO ABROAD, TRAINING ACROSS WESTERN EUROPE. SHE WORRIES ABOUT HER PARENTS AND SISTER, WHO LIVE IN DNIPRO, A CITY THAT'S OFTEN ATTACKED BY RUSSIA. >> HAVE A NICE DAY, GOODBYE. I DIDN'T KNOW WHEN I'LL SEE AGAIN. BUT MY FATHER SAY YOU SHOULD GO. YOU SHOULD SHOW THE WHOLE WORLD WHAT HAPPENS IN OUR COUNTRY. >> THAT'S A WORLD RECORD. >> WORLD RECORD! >> Reporter: DESPITE THE STRAIN, SHE HAS GONE FROM SUCCESS TO SUCCESS, AND THIS MONTH BROKE A 37-YEAR-OLD WORLD RECORD. >> IT'S MY JUMP, MY COMPETITION FOR MY COUNTRY, FOR THE SOLDIERS. >> I FIGHT FOR MY COUNTRY. I'M ALWAYS PROUD TO BE UKRAINIAN. >> Reporter: BOGDAN AND JAROSLAVA, BOTH SAY THE WAR IS MOTIVATING THEM TO SHOW THE WORLD THEY UKRAINE IS STILL STANDING STRONG. RICHARD ENGEL, NBC NEWS, KYIV, UKRAINE. >> THAT INSPIRING JOURNEY TO GET RIGHT HERE TO PARIS. THAT'S "NIGHTLY NEWS" FOR THIS THURSDAY. THANK YOU SO MUCH FOR WATCHING. I'M TOM LLAMAS. HAVE A GREAT