Obelisks are stone columns made in ancient Egypt almost 4,000 years ago. Some were taken as trophies by invading armies and are now in cities such as Istanbul, Rome, London, Paris and New York. More recently people have built memorials based on the design of obelisks. A column commemorating the battle of San Jacinto near Houston, Texas, USA, is the world’s tallest monument at 174 m. It was completed in 1939. The Washington Monument, Washington DC, USA, was completed in 1884. It is 169 m tall, made of 36,491 stone blocks on an iron frame and weighs 82,421 tonnes. It was the world’s tallest structure for five years until it was overtaken by the Eiffel Tower in 1889. The Wellington Monument in Dublin, Ireland is a stone obelisk made to celebrate the victories of the Duke of Wellington. It was completed in 1861 and is Europe’s tallest obelisk at 63 m.