People may be unaware when they are walking around the centre of Bristol, that beneath their feet is a warren of underground passages.

Some of the tunnels date back to the 12th century when Bristol was the centre for wine imports.

The wine was stored in magnificent stone caverns which have survived the bombing of the second world war.

Many of these underground tunnels were inter-linked, making it possible to walk from Corn Street under the centre, to Castle Park.

The book, 'Secret Underground Bristol', written by Sally Watson, invites the reader to look over the edge of the river wall by the ambulance station near Castle Park to see an entrance to the moat that once went around the Castle.

Sally studied archaeology at the University of Bristol and spent a lot of time exploring the city's underground history, much of which is now not accessible to the public.

"All periods of Bristol history are captured down there", Sally Watson told BBC Bristol.

From the caves which were used when the city was a centre for smugglers, to bunkers where the BBC operated during the war.

One of the highlights of the book is the old stone mine near the Box tunnel.

"The mine was used to house the RAF control after the BAC had been bombed in 1941", said Sally.

"It's like a set from the TV show Mash with murals on the wall and the menu still hanging up in the canteen area," she said.

Sally is keen to talk to anyone who worked at BAC at the time when production was taken underground.

You can Email Sally at sally@watnot.free-online.co.uk

'Secret Underground Bristol' is published by Broadcast books priced £14.95.