St Paul's Cathedral is an Anglican cathedral in London. As the seat of the Bishop of London, the cathedral serves as the mother church of the Diocese of London. It sits on Ludgate Hill at the highest point of the City of London and is a Grade I listed building. Its dedication to Paul the Apostle dates back to the original church on this site, founded in AD 604. The present structure, dating from the late 17th century, was designed in the English Baroque style by Sir Christopher Wren. Its construction, completed in Wren's lifetime, was part of a major rebuilding programme in the city after the Great Fire of London. The earlier Gothic cathedral (Old St Paul's Cathedral), largely destroyed in the Great Fire, was a central focus for medieval and early modern London, including Paul's walk and St Paul's Churchyard being the site of St Paul's Cross.

The cathedral is one of the most famous and most recognisable sights of London. Its dome, framed by the spires of Wren's City churches, has dominated the skyline for over 300 years. At 365 feet (111 m) high, it was the tallest building in London from 1710 to 1963. The dome remains among the highest in the world. St Paul's is the second-largest church building in area in the United Kingdom after Liverpool Cathedral.

Services held at St Paul's have included the funerals of Admiral Nelson, the Duke of Wellington, Winston Churchill and Margaret Thatcher; jubilee celebrations for Queen Victoria; inauguration service for the Metropolitan Hospital Sunday Fund; peace services marking the end of the First and Second World Wars; the wedding of Prince Charles and Lady Diana Spencer; the launch of the Festival of Britain; and the thanksgiving services for the Silver, Golden and Diamond Jubilees and the 80th and 90th birthdays of Queen Elizabeth II. St Paul's Cathedral is the central subject of much promotional material, as well as of images of the dome surrounded by the smoke and fire of the Blitz.

The cathedral is a working church with hourly prayer and daily services. The tourist entry fee at the door is £20 for adults (August 2020, cheaper online), but no charge is made to worshippers attending advertised services.The nearest underground station is St Paul's, which is 130 yards (120 m) away from St Paul's Cathedral.