London is famous for its Underground subway system, ('The Tube') For fast and easy transport here are some helpful sites.
Transport for London
The Tube
London Buses
Docklands Light Railway
Walking Tours
Many companies run organised walks around London. Arguably the best is Original London Walks www.walks.com which has walks on everything from Sherlock Holmes to Jack the Ripper. If you want to do it yourself Green Chain walks connect many of the green spaces of south - east London www.greenchain.com and Time Out publishes an excellent guide, The Time Out Book of London Walks.