World's tallest building, The Burj Khalifa is a massive skyscraper in Dubai, United Arab Emirates that reaches an impressive 828 m (2,717 ft) height. Construction of the building commenced on 6 January 2004 and concluded on 1 October 2009. It was built as part of a larger development called Downtown Dubai and cost US$1.5 billion to complete. While originally named Burj Dubai, it was later renamed to Burj Khalifa in honor of the president of the United Arab Emirates, Khalifa bin Zayed Al Nahyan.