Here are a few ideas.
-Over a period of time, visit all the protected views of St Paul’s and take a picture of the cathedral from each one. It took me ages to line up my phone with the telescope viewer to get a pic from Richmond park!
-Visit an area with a lot of blue plaques, and then look up the life story and achievements of the people involved.
-Read up on the history of Bankside and Borough, and then walk round the area - The Globe, the site of The Tabard Inn, The Clink, the ruins of the Bishop of Winchester’s Palace, Cross Bones graveyard and lots more, and have a goats milk ice cream from Borough Market.
-Visit all the places on the Monopoly board - in order, if possible. Do it on foot and by bus rather than the tube. Take a picture of each, print them out, and stick the to your family Monopoly board.
-Make a list of songs about London places - everything from nursery rhymes to pop. Then let them go to each location, and make a video of themselves singing that song. So, for example, “London Bridge is falling down” on London Bridge, “Let’s all go down the Strand” on the Strand and “Waterloo Sunset” on Waterloo Bridge.