Caches should be bring you somewhere lovely. There are not many pedestrian bridges over the River Thames and this is a simple but elegant example taking you to great height. The official name is Hart's Weir Footbridge and it was built in 1879. Rainbow bridge is its local name because of its shape. I did wonder about this being on the bridge, but there is no where secret to hide it. The challenge is not on the bridge, but on a nearby tree over looking the bridge.
Hfrq gb or n ovg bs n pyvzo, ohg V ercynprq vg jvgu bar nobir sybbqvat yriry, ohg abg arrqvat pyvzovat.