The Williamson Tunnels are a series of extensive subterranean excavations, of unknown purpose, in the Edge Hill area of Liverpool, England. They are thought to have been created under the direction of tobacco merchant, landowner and philanthropist Joseph Williamson between 1810 and 1840. Although popularly described as "tunnels", the majority comprise brick or stone vaulting over excavations in the underlying sandstone. The purpose of the works remains unclear and remains a subject of heavy speculation; suggestions include commercial quarrying, a philanthropic desire to provide employment, and Williamson's own eccentric interests.
After being gradually infilled with rubble and spoil during the late 19th and early 20th centuries, they remained largely inaccessible until archaeological investigations were carried out in 1995. Since then volunteers have rediscovered and excavated an extensive network of tunnels, chambers and voids across several sites, with sections open to the public. Guided tours are available at the Williamson Tunnels Heritage Centre and the Friends Of Williamson's Tunnels, and excavation continues as volunteers continue to uncover new sections.