This walk goes underground at various places on the north and south banks of the Thames to show you a secret passageway that stretches for a quarter of a mile along the river, under the new 'London Bridge City' development. We also highlight a 'ghost' underground station at 'Mark Lane' together with hidden tunnels under the modern London Bridge, and we also look at the history of the 'Tower Hill Subway' system (a way of crossing the Thames before Tower Bridge was even thought about).

In addition to the underground highlights, this walk also features the history of the old London Bridge, and a visit to the Hays Galleria; a fantastic example of a redeveloped wharf which was once home to the famous tea clipper ships.

This walk starts at 11.30am at the giant sundial above Tower Hill station. The walk finishes at 12.45 close to Tower Bridge.

Each walk costs £5 per person with proceeds going to 'Cancer Research UK' and 'Oxfam'.