Marlow suspension bridge has a unique link with the Széchenyi Chain Bridge in Budapest.
There are only two bridges remaining built by the designer.
The bridge opened in 1832 and was designed, supervised and constructed by William Tierney Clark.

In the 1950's it was proposed to replace the bridge with a modern concrete monstrosity.

But the Marlow Bridge Preservation Committee opposed this plan.
In 1965 the Suspension Bridge was faithfully reconstructed by Buckinghamshire County Council and limited the bridge
to 3 ton weight with single file traffic and no lorries.

You are looking for a Micro Cache in the middle of the bridge.
Walk from Marlow High Street towards the bridge and walk on the left side facing the weir.