All Hallows by the Tower church was founded in 675, making it one of the oldest churches in England. A thousand years later, in the Great Fire of 1666, it was nearly destroyed and owes it survival to Admiral William Penn, the father of quaker Pennsylvanian founder William Penn. Admiral Penn instructed his men to demolish the buildings surrounding the church, thus preventing the fire from spreading to it. 
The church has ties with two important Americans. The first is William Penn, whose father was so closely associated with the church and who was himself baptised as an Anglican at All Hallows in 1644. The second is John Quincey Adams, who was married to his wife Louisa at the church in 1797. Records of both these events can be found at the church's undercroft museum, located in the crypt.