I have started doing some light research into a possible "Metro Project 101". As mentioned there are 101 metro stations in the city, the first ones opened in 1898, the latest so far in 2016. The highest station is at 469m/1540ft above sea level, the lowest one is below sea level by 20m/65ft. Only 17 of the stops are actually below ground.
This will not be something quickly done with. Just visiting all 8 end stations will take 7 hours 57 minutes pure travel time (there and back including turnaround time). Of course, this will multiply quickly as it's completely unrealistic to cover, say, all 18 stations on western line 1 in one go. Let's say 24 hours pure travelling time, then.
If one assumes a half an hour stop at each station that will add 50.5 hours. Apart from the 12 stations on the circle line between home and work this sounds like mainly a weekend project. Let's subtract 10-12 hours for the cirle line stations and we're left with 60 hours of "work". Max 4 hours spent on this during a weekend (let's keep it enjoyable, ok?) means 15 weeks - except that some weekends are already full. Say 22 weeks, then.
And to make any project even remotely realistic one has to double all the estimates, right? I'd be very happy with getting through this in a year.
Then comes curating the images. And if one puts down that amount of work it might deserve a blog of sorts...