MemoryLane

Google Street View lets you go anyplace on Earth that Google's cameras have previously visited (which is pretty much everywhere) and explore that place interactively as a 3D virtual world.  Sometimes the pictures are a bit out of date, but the system is still both interesting and useful.

In one way, however, the pictures are not out of date enough.

There are now many complete 3D computer models of cities as they were in different historical eras.  The picture above, for example, is a still from a video fly-through of a model of seventeenth century London created by De Montfort University.  But a directed video fly-through is not the same as a virtual world that you can explore interactively.

So why not integrate these models with Street View?  You could have an extra slider on the screen that would allow you to wind back to any point in history and walk round your location at that date.  There would be gaps, of course, which could be filled in as more models became available.  And also some of the buildings and other features would be conjecture (the De Montfort model is accurate as far as the known information is concerned, but it is set before the Great Fire so there are interpolations).  As long as these were flagged as such there would be no danger of confusion.  Street View does allow you to go back through Google's scanned archive, but in the seventeenth century they were quite a small company without the resources needed to do the scanning.

On your 'phone, the historical data could be superimposed on the modern world in augmented reality as you walked in it, Pokémon Go style, giving you details of superseded historical architecture in your current location.

And when there were enough data we could train a neural network to predict the likely buildings at a given location on a given date from the buildings preceding them in history.  Running that on the contemporary Street View would give us an idea of what our cities might look like in the future...