Opened for the Olympics as a Thames crossing between the ExCeL convention center and the O2 dome, it’s an enclosed, 10-person gondola (you’ll share with strangers) with (barely audible) recorded commentary that shuttles between two places most tourists never go. It’s too far from the City to be a panoramic substitute for the Eye or the Shard. The ride takes 5–10 minutes, costs what a Tube ride does, and you can use Oyster.