Most leaning building in the world: Capital Gate by RMJM,

Capital Gate, the iconic leaning building in Abu Dhabi, reached halfway point. The building, designed by international architects RMJM, will lean 18 degrees westward, 14 degrees more than the Leaning Tower of Pisa.
To make this possible, the central core of the building slants in the opposite direction to the lean of the structure, and it straightening as it grows. It sits on top of a 7-foot-deep concrete base with a dense mesh of reinforced steel. The steel exoskeleton known as the diagrid sits above an extensive distribution of 490 piles that have been drilled 100 feet underground to accommodate the gravitational, wind and seismic pressures caused by the lean of the building.

A gigantic internal atrium, including a tea lounge and swimming pool suspended 263 feet above the ground, has been constructed on the 17th and 18th floors, the halfway point of the 35-story, 525-foot tall tower.
Capital Gate will house Abu Dhabi’s first Hyatt hotel – Hyatt at Capital Centre, a presidential- style luxury, 5-star hotel and will provide 200 hotel rooms for Abu Dhabi and will serve ADNEC’s (Abu Dhabi National Exhibitions Company) visitors and exhibitors as well as international business and leisure travelers.