The Grimaldi Building, Pentonville Road N1

This keystone, high on a building that looks like an 18th century church, is the face of the man who invented the clown - Joseph Grimaldi.

The Grimaldi Building is an office block, designed by Allies and Morrison in 1988 to replace the redundant church of St James. The church authorities had obtained planning permission for an office block in a replica of the old church, a sop to conservationists who had hoped to save the building. A&M respected that in as far as the front is a repro church, with the anachronistic addition of Grimaldi's head, though the building behind is not.

Grimaldi is buried in the old churchyard, a simple headstone with a railing. He was born in London in 1778 to a stage family, becoming a child star. He began to make the role of Clown in the Harlequinade his own, and was so successful that Clown became the principal part, elbowing out poor old Harlequin.

He is credited with inventing the clown's iconic makeup and much of the physical comedy. Indeed, his comedy was so physical he had to retire through ill health. 

In 2010 an extraordinary additional memorial was added by the artist Henry Krokatsis. It is a pair of coffin-shaped brass plates, one for Grimaldi and the other for his patron and mentor, the song-writer and composer Charles Dibdin (of Tom Bowling fame).

When you tread on the bronze plates they ring at various pitches, so you can play a tune by almost literally dancing on their graves. The notes of Grimaldi's coffin are tuned so you can play his signature tune Hot Codlins (hot codlins were toffee apples).