Deep beneath the Edge Hill district of Liverpool there lies a mysterious network of tunnels almost two centuries old. It is a largely uncharted labyrinth and contains many large caverns. The network is even said to contain complete houses.

The tunnels were built in the 1820s and 1830s by tobacco merchant Joseph Williamson, known locally as “the mole of Edge Hill”. Oddly, they seemed to serve no apparent purpose. No one really knows for sure why they were built. Now, a section of the Williamson tunnels has been restored by local enthusiasts and opened to the public.

Joseph Williamson (1769-1840) was born in Warrington. As a boy, he moved to Liverpool to work for Richard Tate, a tobacco merchant. He worked hard and progressed through the company. In 1802, he married Tate’s daughter, and shortly afterwards inherited the firm, which he ran until he retired in 1818.

In his later years, Williamson busied himself building houses on land he had acquired in Edge Hill. The construction work provided some much-needed employment for the recently demobbed troops returning from the Napoleonic wars. But as well as building upwards, the mole of Edge Hill burrowed downwards. He set hundreds of men to work on the construction of an elaborate tunnel network beneath his estate.

Williamson’s close friend, the historian James Stonehouse, said of the strange tunnels: ”(They) appear to be utterly useless. We have stupendous works without perceptible motive, without plan, meaning, reason or form.”

There are a number of theories about the motives behind this underground kingdom. Some say Williamson simply wanted to indulge an eccentric fascination with tunnelling, others that the labyrinth was his refuge from the outside world. One anecdote says that he built a tunnel from his house to St Mary’s, the church he attended, so that he could make the journey there on rainy days without getting wet.

One thing is certain: he did not build the tunnels to provide a spectacle.

In fact, he allowed few to visit them, and said that they were “not showshops, nor he a showman”. In the end, the most likely explanation seems to be that he built the network to create jobs for returning troops at a time of very high unemployment.

When Williamson died, his tunnel system lay half-forgotten beneath the streets of Liverpool. Over the years, many of the tunnels were filled in because they were considered to be unstable. Recently, though, a section has been excavated, restored by the Joseph Williamson Society and opened as a tourist attraction.

Visitors to the Williamson Tunnels Heritage Centre can enjoy a fascinating glimpse into Williamson’s eerie underworld. Those who attend must don hard hats before embarking on a 45-minute guided tour of the tunnels.

The tour begins in the 20-metre-long Corner Tunnel. This dimly-lit passageway, with its sandstone bedrock and brick ceiling, smells of damp earth and stone. It has an upper chamber, once used as a cellar by a tenant overhead.

The Corner widens into a cavern 8m deep, then leads into the claustrophobic Small Tunnel. This, in turn, leads to a modern concrete passageway connecting it to the Double Tunnel: two large caverns, one on top of the other, separated by a brick arch.

The Double Tunnel houses displays of artefacts unearthed during the excavation of the site: earthenware, stoneware, bottles and jars, crockery and tobacco pipes. At the end of the Double Tunnel is the Well Tunnel, which once supplied water to the tenants of Mason Street, up above.

The Heritage Centre runs various tours and workshops for schools. For Key Stages 2 and 3, there is the Tunnel Vision tour in which pupils search for clues about how and why the tunnels were built. A workshop called Pieces from the Past allows pupils to analyse a collection of the unearthed artefacts.

For KS3-4 pupils, the Leisure and Tourism tour gives pupils a valuable opportunity to learn about the development of the tunnel network as a heritage attraction. There are also tours for post-16 pupils studying leisure and tourism.

Williamson Tunnels Heritage Centre. Tours and workshops cost pound;2 for school-age children; pound;3 for post-16 students. For more information contact Barbara Price, telephone 0151 709 6868www.williamsontunnels.co.uk;email: enquiries@williamsontunnels.co.uk