The prosperity of Perth has always relied on a safe crossing of the river Tay into the towen. In 1621 the main bridge was washed away in a flood. It took until 1771 before a replacement was built. John Smeaton, architect of the Eddystone Lighthouse, was commission to design a new bridge. The bridge has survived many floods since then and is still in use today, having been widened in the 19th century. Map location.