The April culmination of March Madness was on full display Friday in downtown Minneapolis as tens of thousands of basketball fans hit the streets and skyways, reveling into the night in activities that stretched from U.S. Bank Stadium to the Minneapolis Convention Center and along Nicollet Mall.

Hoops mania got an early start, with the stadium opening its doors to the public at 10 a.m. for a free daylong look at the reconfigured interior and the four remaining teams in the NCAA men’s basketball tournament.

The fans blew the doors off. Some 36,000 of them showed up — far more than the pre-event estimate of 20,000 to 30,000 — to watch the teams practice before Saturday’s semifinal games in the one-and-done tournament.

Ten-year-old Fen Stumpf of Columbus, Ohio, was in the stadium Friday after his two grandmas told him they’d take him on a dream birthday trip of his choice. He picked the Final Four, and 12-year-old cousins Johnna and Morgan Miller got to tag along.

They waited in the longest line in the stadium for more than an hour to get more than a dozen autographs from collegiate all-stars, including Stumpf’s favorite, Kyle Guy of Virginia, who happily posed with the birthday boy.

Stumpf, a guard on his traveling team back home, shrugged off the gray, rainy weather.

“It’s awesome,” he said. “I’ve always wanted to come.”

When at last they reached the front of the line, Johnna Miller took off her sneakers and had the players sign them.

Fans reported smooth access and security checks upon entering the building. Inside, the concourses and seats were buzzing with people.

Auburn hit the court first for an hourlong open practice that included some showy, crowd-pleasing alley-oops. Getting in their own warmups was the 30-person Auburn pep band. Drummer Jim Shaw said everything has been “completely awesome” so far.

The Minnesota Vikings’ home got a new look for the weekend event. The building’s translucent ceiling and giant glass doors were covered with custom curtains that cost $5 million. Additional seating was added to bring spectators closer to the court at the center of the Vikings’ field. In all, 72,000 fans are expected to attend the games Saturday and on Monday — when the championship game will take place.

Dan Skog isn’t planning to attend any Final Four games, but the Blaine father of two took the day off work Friday and brought his kids downtown to check out the giant Ferris wheel set up for Nicollet Mall’s Final Four Tip-Off Tailgate party and take part in the Minneapolis Convention Center’s Final Four Fan Fest.

“I know this doesn’t come around here very often,” he said. “It’s been a really great family event.”

Inside the center, thousands gathered to try their hand at family-friendly Fan Fest sports activities like a free throw contest, a golf simulator and a giant game of beer pong without the beer, involving huge plastic cups and basketballs.

Brian Mollett and son Pacey, 11, from Webbville, Ky., gave the scene a thumbs-up.

“So far, so good,” said Mollett, adding that it was the pair’s fifth consecutive time attending a Final Four event. “We come to watch the game, even though this is fun.”

For the Minnick family from East Lansing, Mich., Michigan State’s spot in the Final Four meant a reason to finally visit Minneapolis — and they’ve loved their reception so far, including signs at the airport welcoming basketball fans. They shrugged at Friday’s dreary weather.

“It’s not a warm one, but we are still making this a spring break vacation,” said Summer Minnick, who met husband Brandon at Michigan State.

“Overall, it’s been a great atmosphere,” Brandon Minnick said. Still, he had one small complaint about the friendly locals who comment on the family’s dark green and white Michigan State gear:

“Everyone here keeps saying, ‘Go Michigan’ when they see us,” he said. “But it’s Michigan State. We keep just wanting to correct them.”

By early afternoon, the skyways were bustling with fans. Dozens of volunteers helped direct visitors through the skyways. Several visitors paused for photos in the glass passageways into the IDS Center as bumper-to-bumper traffic moved slowly below. Others held their phones to the skyway windows for a better angle to photograph the Ferris wheel on Nicollet Mall.

“It’s cool to see Minneapolis get this attention and publicity,” said Maureen Hartung of St. Paul, who brought her 6-year-old son Miles. “I keep telling him that he’ll probably have to wait until he’s my age to see this come to the city again.”

“There’s so much going on for families,” she said. “You could spend all weekend visiting them all.”

Ericson Lachica, of Arlington, Va., said he’s not rooting for any particular team. He’s just here for what he hopes is a weekend of exciting games.

Lachica teamed up with a perfect stranger, Jesse Laliberte of Coon Rapids, to win a chicken wing eating contest. Hunched over a table in a wrestling ring, he and Laliberte took turns, eventually downing 20 extremely spicy “Blazin’” wings in just 10 minutes with no napkins and no water. The rival team lasted only six minutes.

After sunset, thousands of jovial fans strolled down Nicollet Mall, dancing to live music along the route. Under the glowing Ferris wheel, visitors dined on heated patios and played yard games.

Dylan Graetz and Adam Schulman of Memphis said they were struck by Minneapolis’ Midwestern charm.

“The city is so clean. Everyone is so nice,” said Graetz, a lifelong Virginia fan whose family was flying up for the occasion. “It’s been a great reception so far.”

She and Schulman, a Virginia alum, joke that they owe their relationship to the team. They started dating after she told him: “I’m just looking for someone to watch UVa basketball with.”

Staff writers Liz Sawyer and Erica Pearson contributed to this report.