One particular building I visited is the Wesley Chapel and Wesley House. These buildings are over 200 years old. They were built back when John Wesley was preaching and gathering a flock for a new church. I also enjoy seeing the various buildings along the Thames, such as Parliament and Westminster Abbey. The London Tower and the Tower Bridge are also great landmarks in the city.
Several boats operate along the river showing off the sights from the waterway.
The buses operate two routes, a Blue and a Red route which take you by numerous different landmarks. You may hop off and walk around and then hop back on the bus for more of the tour. If you take both routes and the boat and hop on and off at a couple of different places you can easily fill your whole day. Eating in London can be fun. There are all kinds of food available.