I-Spy

We went on the London Eye during that trip. I would advise, if you want to go, to take a disabled friend. You manage to queue-jump most shamelessly, get cheap rate tickets, and a less crowded capsule!

It's surprisingly high - more than it looks. My own "flying dreams" tend to happen at ten(s) of meters at most. This was ten times higher - about 400 feet - enough to look over all the rooftops, and out to the hills to north and south. Well worth it, even if it is only 25 minutes.