All Hallows (meaning 'all saints'), which dates from AD 675, survived virtually unscathed by the Great Fire, only to be hit by German bombs in 1940. Come to see the church itself, by all means, but the best bits are in the atmospheric undercroft (crypt), where you’ll discover a pavement of 2nd-century Roman tiles and the walls of the 7th-century Saxon church.
Free 20-minute tours are available between 2pm and 4pm most weekdays from April to October.
In the nave, note the pulpit taken from a Wren church on Cannon St that was destroyed in WWII and, by the south door, a Saxon archway and a beautiful 17th-century font cover decorated by the master woodcarver Grinling Gibbons. The church has two strong American connections: William Penn, founder of Pennsylvania, was baptised here in 1644 and schooled in what is now the Parish Room; and John Quincy Adams, sixth president of the USA, was married here in 1797.