Dubai has opened the world鈥檚 tallest building as the emirate tries to re-establish some of the optimism it experienced prior to its financial crisis. Sheikh Mohammad bin Rashed al-Maktoum, the ruler of Dubai, inaugurated the tower - originally called Burj Dubai - as Burj Khalifa in honour of Sheikh Khalifa bin Zayed al-Nahayan, the president of the United Arab Emirates. At a height of 828 metres, Burj Khalifa soars over its nearest rival - the Taipei 101 in Taiwan which rises to only 508 metres.