I did the fist walking tour which starts at Embankment Tube Station near Trafalgar Square on the Thames and goes around the Strand and up through Covent Garden and I found it fascinating. Tons of little things I would never had noticed along with lots of history and hidden alleys to duck into and such. A lovely hour and half stoll. I walk fast so it could take you a little longer. And bring your camera to take pictures. Lots to see and well worth your time.