The giant crane is on the island to the south of Rickety Rig, and it’s difficult to miss the bright orange monolith. This area is likely to get very busy quite quickly, so try to either land on the crane or nearby at the Rig so you can grab a few materials and weapons.
Fortnite: Chapter 2 Season 3 - Dance on top of the Crane at Rickety Rig
Before you begin, make sure to equip your favourite dancing emote before the match begins then head over to the southwest corner of the map to find Rickety Rig. You can enter the buildings leading up to the crane to get most of the way there, then you can build some stairs to reach the top. Make sure to watch out for other players who arrived first, as they might try to set up a sniping vantage point to take you out.
Once you’ve reached the top, use your dancing emote until the challenge registers as complete. If you missed the beginning of Season 3, you can check out all the map changes here, as well as all the Aquaman challenges. You can also check out how to open the vault at Catty Corner, where to find Loot Sharks, Deadpool’s floaties and the Gnomes at Homely Hills here.