It's the stage specially built for KÀ by Cirque du Soleil which perform numerous shows per week at the MGM Grand- Vegas
The Main Stage feature is a 25- x 50-ft Sand Cliff deck. It weighs more than 100 tons and is lifted more than 70 ft in the air!
How the stage works:
The Really Technical Explaination
Technical Director Erik Walstad and
Operations Production Manager Keith Wright
Wikipedia Says: "Unlike other Cirque du Soleil performances, Kà offers four pre-shows. Once the house opens, guests are greeted by the villagers of Kà ("Gatekeepers") with different professions such the mayor and his wife, the healer, the gossip, and so on.
Twenty minutes before curtain, two musicians enter the lobby and climb up to two stringed instruments specially designed for Kà and integrated into the architecture.
Ten minutes before the show, actors appear in the metal framework to the left and right of the stage and perform flips and leaps assisted with ropes to dive into the audience and attempt to scare viewers."