To get a handle on the party’s sheer enormousness, it was best to ascend the breezy battlements of the four-story, castlelike structure. High-definition projectors beamed pink and purple images on the fortress walls. Rays of light sliced through fog like Bat signals. And a sea of tiny heads, as big as a city block, bobbed beneath palm trees and airborne KV2 Audio speakers.

This was not Las Vegas, Miami or Zrce beach in Croatia. A quick westward glance revealed the tip of the Empire State Building glowing like a cigarette cherry.

“I love this scene,” said Tengiz Iliaev, 34, who was standing on the highest turret. A native of Tbilisi, Georgia, he wore a woven duckbill hat and a heart-shape medallion. “What else do you want? A place where you can parachute?”

After a year of false starts and legal imbroglios, the contentious nightclub Brooklyn Mirage opened last Saturday as a huge, architecturally ambitious destination for deep house and techno parties.