The things we do for that crazy roof on the former KeyArena

The arena at Seattle center (that we used to call KeyArena) is being rebuilt to house Seattle’s new hockey team.

There’s only one part the old structure that will remain: Its landmark roof. That's complicated the project.

From the top of Queen Anne, you can see the roof of KeyArena. You can tell it was built in the 1960s, because it kind of looks like the roof of a fast food restaurant.

Jill Crary, redevelopment director at Seattle Center, said it’s worth preserving. "I like how it hugs the ground and how modest it is. A lot of these big arenas — they’re huge," Crary said.

But to fit it all under that modest roof, they’re digging down. Seats will be really steep and there’ll be much less concrete to block views.

Over time, the project cost has crept up nearly 50 percent. It could cost as much as $930 million by the time it's done. Taxpayers won't pay for that though, because the arena's privately funded.

Ken Johnsen is an executive in charge of construction.

"We are going to have to demolish all of this concrete that is holding this up," he said, standing in the middle of the arena.

If you pass the arena later this year, the roof may appear to be floating above a giant hole in the ground, held up by nothing except some scaffolding.

The contractor will then build up from that hole to meet the roof.

"It is a brand new arena under an iconic, historic roof," Johnsen said.

If everything stays on schedule, it will open just in time to host the NHL draft and the Seattle Storm's 2021 home games.