Sheikh Mohammad bin Rashed al-Maktoum, the ruler of Dubai, on Monday officially opened the world's tallest building, which stands more than 800 metres high. Sheikh Mohammad unveiled a plaque and gave a brief speech during which he renamed the building the "Burj Khalifa," after the United Arab Emirates president, Sheikh Khalifa bin Zayed al-Nahayan.
The exact height of the tower remains uncertain. The building's developer has said it stands more than 2625 feet (800 meters) tall.