Old St Paul's Cathedral was the medieval cathedral of the City of London that, until 1666, stood on the site of the present St Paul's Cathedral. Built from 1087 to 1314 and dedicated to Saint Paul, the cathedral was the fourth church on the site at Ludgate Hill. Work on the cathedral began during the reign of William the Conqueror and took more than 200 years, construction was delayed by another fire in 1135. The church was consecrated in 1240 and enlarged again in 1256 and the early 14th century. At its completion in the middle of the 14th century, the cathedral was one of the longest churches in the world and had one of the tallest spires and some of the finest stained glass.