It doesn't look like much, because it isn't much any more. However, this used to be the site of Hotwells Station (formely Clifton Station, before the opening of Clifton Down and the continued existence of Clifton Bridge meant the proliferation of stations with "Clifton" in the name warranted some disambiguation.)

Nestled in this little nook underneath the suspension bridge, it was the Bristol terminus of the Port Railway and Pier, whose aim was to avoid increasingly big ships having to wait for the right tides to come into Bristol and unload. They ran a line from Hotwells Station, here, to a deep-water pier at Avonmouth so the ships could moor there regardless of the tide, and transport cargo and/or passengers to and from Bristol, with this being the Bristol terminus. Work started at Shirehampton in 1863.

Originally this was an isolated line, but it was later hooked up to the rest of the rail network by the Clifton Extension Railway, and a tunnel under Clifton. That's a connection we'll be exploring a bit today, at least with a few of its visible above-ground bits.

The line saw its biggest use during the First World War, as dockers, munition workers, hospital trains and so forth ran back and forth between Bristol and the port. They even added an entire extra platform, Hotwells Halt, just down the road, to cope with the increase in traffic, platform space being at something of a premium in this unexpandable little nook, which runs from the bridge to the first of two tunnels in the cliff face to head onward to Sea Mills.