What is in the Burj Khalifa?

Answer 1

Residential apartment suites, business suites, offices, shopping areas, parks and atrium spaces, and a large number of elevators and escalators (one type of elevator is among the fastest ever built).

Answer 2

The skyscraper in Dubai (UAR), the tallest in the world, was originally intended to be entirely residential. But marketing the expensive building became more difficult and a mixed use was established: it includes a large hotel as well as office and retail space.