I appreciate this hobby.

I've visited San Francsico a few times but haven't been since 2007.

At one point, back in about 2013 or 2014, I got a little bit obsessed with the Hetch Hetchy aqueduct. It started innocently enough (reading an article about the Pulgas Water Temple), and I ended up spending many evenings in bed using Google Earth and Google Maps street view to trace the route of the aqueduct and look at the things around it. Where the pipes run under cities it's easy to see their "mark" on the land (since no permanent structures are permitted to be built above them). Following them up into the mountains was fun, too.

A few years later I got into looking at abandoned rail lines in the Midwest and spent evenings "flying" the routes of old railroads. They're similar to the aqueduct insofar as you can see the "scar" they've left on the (and in the oddly-shaped parcels of land left after they were sold-off).

I do the same thing with streams and other wetlands in my area. Another interesting Google Maps curiosity is the 'overpass to nowhere'[1] over I-84 in Farmington, CT.

[1] https://maps.app.goo.gl/QUgug3fwmPeAC2Wu8