A.Each clock face on the Tower of Big Ben has an area of 23 square feet. They stand 180 feet above the ground. The clock was designed by Augustus Pugin.
Q.What is the world's tallest building
A.The Burj Khalifa in Dubai is 828m (2,717ft) tall and the tallest man-made structure ever built. It cost $1.5 billion to build, and opened in 2010.
Q.Where is London's highest point
A.London's highest point is Parliament Hill, Hampstead Heath (441 feet, or 134.4 metres above sea level). The highest building is One Canada Square (235m).