The Clifton Suspension Bridge is held up by second-hand chains. When Isambard Kingdom Brunel’s Hungerford Bridge in London was demolished in the early 1860s, its ironwork was bought and hauled west to finish this crossing over the Avon Gorge, a project that had been stalling for decades.

Brunel’s design won a competition in 1831, yet the bridge only opened in 1864, five years after his death. He had imagined smooth, Egyptian-style towers topped with sphinxes. Instead, the engineers who finished the job left the stone rough and beefed up the roadway, and people still argue over who deserves the credit.

VoiceMap’s self-guided audio tours follow Brunel from the SS Great Britain to the bridge’s official viewpoint, tracing how he plotted to cross an ocean and a gorge in the same decade. Others climb through Clifton Village, explaining how the fashionable Hotwell Spa once bubbled away directly below.