The Tower of London served for 900 years as a fortress, residence for kings, armory, treasury, prison, and place of execution. The National Gallery has one of the largest collections of Western European paintings, though it is hard to believe it started with only 38 paintings. St. Paul's Cathedral's magnificent dome, built after the original burned down in the Great Fire of London, has been a notable landmark. Madame Tussauds wax museum was established in London by sculptor Marie Tussaud and has branches in 10 other cities. The Greenwich Observatory was founded by King Charles II to study astronomy and fix longitude measurements. Tower Bridge, sometimes confused with London Bridge upstream, is an iconic drawbridge in London that opened