St. Paul's Cathedral houses Great Paul, Britain's largest church bell in current use, weighing over 16 tonnes and rung only for special occasions. Sir Christopher Wren's masterpiece rose from the ashes of the Great Fire of 1666, which had destroyed 80% of the old City, including 87 churches and the medieval cathedral that had stood in St. Paul's place before.

The Portland stone, recently restored to its original light yellow after centuries of London soot had turned it dark grey, gleams above a city that Dickens once described as drowning in fog, with only the great dome seeming to "die hard" above the vaporous sea. Inside the south west tower, the Geometric Staircase appears to float upward without support, its architectural illusion captured in the Harry Potter films as the Divination Stairwell.

VoiceMap's self-guided audio tours trace Wren's fingerprints across the rebuilt city, following Dickens through ancient alleyways, and revealing how the cathedral's dramatic silhouette connects to everything from Harry Potter's wizarding world to the modern Millennium Bridge, once so wobbly it had to be closed for a year.