Great thread! I didn't know it existed.

During the Edo period, the Tokyo Bay shoreline was much further inland. In the Hiroshige print shown below, the shoreline comes almost up to the Old Tokaido Highway at the Shinagawa Outpost, which was very close to what is now the JR Shinagawa train station.



During this time, a person needed official approval to enter and leave the city (or any other city) so the outposts were heavily guarded.