While in Liverpool this year, I visited Williamson’s Tunnels with one of my daughters. I found it interesting. There are a lot more tunnels in Liverpool that have been closed up or not been found yet or being excavated.
The tunnels that are open to the public are not extensive but the history is interesting and the guides are good with knowledge and answering questions. Well worth a visit.
This is a link to their website http://www.williamsontunnels.co.uk/