A small pocket park at 25 Cannon Street, a minute from the cathedral, built around an oval reflecting pool that holds a clean upside-down copy of St Paul's dome. It turns one of the most photographed buildings in London into something you have not seen a thousand times.

Best time: still, bright mornings for a sharp reflection before the wind ripples it. Blue hour, when the dome is lit and the sky still has colour.

Look for: shoot low with the phone or camera right at the water's edge so the reflection fills the frame. Wait for a figure on the far side to break the symmetry, or a pigeon to land and scatter the surface.