One of my recent trips was to London to take part in "The Big Draw".
Sketchers were met at Trinity Buoy Wharf and for about 4 hours we walked (I walked 9 miles in total that day, probably 5 of those were for the sketching) around some amazing sites with people who really knew the area and we stopped for about 10 mins at a time to sketch (I had never heard of it-but will be back as there was SO much to see).
It was really fast paced and totally out of my comfort zone but I loved every minute of it as it forced me to just get something down on paper.
This lighthouse has amazing views inside
and also houses the Longplayer http://longplayer.org/about/
Which is a 1000 year long musical composition!!!
I have never seen anything like some of the exhibits and sculptures here.
We also walked to the Emirates Cable car and caught this (90 meters up in the sky!) across the river to the millennium dome.
There was SO much to see and do this is only a small part of it.
If you are in the London area I recommend a trip there.