The "Sounding Arch" of Brunel's Maidenhead railway bridge
has a span of 128 feet, so we needn't be surprised that the echo is pretty good - hence its name. The bridge has an interesting history that is easy to find elsewhere, but is perhaps primarily famous for its depiction in Turner's impressionist picture Rain, Steam and Speed:
(Local spies report that a nearby bridge engineered contemporaneously has an equally good echo, but this cannot be so as its span is very much less).
Proximal to this fine bridge is an equally fine GvR wall box;
and a drain cover that probably wasn't due to IKB.
Returning to Maidenhead, there was a grand view of the Bath Road vehicle bridge
and a now unusual PO bicycle, outside a sub-PO.
It's possible the bicycle has moved but the bridges are probably still there.