St Paul's Cathedral is one of the most famous buildings in the world, and it is also one of the greatest survivors!
There was once a Roman temple on the site, dedicated to the goddess Diana. Since then there have been four different Christian buildings. The first Christian church was built by the Saxon King, Ethelbert of Kent. Being made of wood it didn't stand a chance and was eventually burnt down. It was rebuilt in stone but that didn't work either as it was destroyed in a Viking invasion. When the Saxons used wood again on the third church, it was doomed to be destroyed by fire again!
When old St Paul's was built in the time of William the Conqueror, stone from Northern France was used and it was much taller and wider than it is today. During the reign of King Henry VIII, financial problems meant there wasn't enough money for the cathedral's upkeep. Parts of it were destroyed and a market place was set up inside selling, bread, meat, fish and beer!