Runners from around the world gathered in New York last night to run up some stairs.
But not just any flights of stairs...
Last night was the 42nd Annual Empire State Building Run-Up.
Competitors race up the famous skyscraper's 86 flights of stairs to the observation deck.
Specifically, that's more than 1,500 stairs.
Runners say it's quite a challenge, as you could imagine.
It takes the best runners about 10 minutes or so to complete the stair climb.
If they took the elevator to the observation deck, it would take under a minute.