The world's biggest indoor bike park just opened 10 stories below ground in Louisville - and it looks spectacular

The owners said they had to cover 320,000 square feet of floor with dirt.

This is what the jumps looked like early on. This photos shows about 5% of the bike park.

A worker smooths out one of the many berms.

This was one of the last structures to be built.

A long view of the park. Those turns looks so inviting.

Green means go for beginners and anyone new to biking off-road.

Blue circles indicate intermediate trails.

Black triangles indicate advanced obstacles like wooden structures and jumps.

A view from the "launch pad" during the construction phase.

A couple of BMXers tested out the jumps.

The park is not just for BMXers and mountain bikers — cyclocross riders are welcome too.

Listen to the owner describe the history of the cavern and the park.

Check out this cool video of riders hitting big air.

Here's another showing riders shredding the jumps.

For BMXers, it's all about the big air.

More information is available on the park's website at LouisvilleMegaCavern.com.