Joseph Pearson

It's very touristy but theatre like the globe theatre is always nice. And the "sky garden" if you want the full view of London, there is a free viewing but you usually have to book well in advance, the restaurant inside is not that bad in terms of price and allows you to skip the long queue.

Museums in both cities are amazing.
In London public museums are free for everyone with only special expo where you have to pay, Paris on the other hand it is only free for under 18 for everyone and for under 25 it's only for Europeans . Do book in advance as they can be very busy.