Here's a fun Friday afternoon time-suck: The National Library of Scotland made freely available online 16,865 historic Ordnance Survey maps covering Greater London and the south east of England, dating between the 1840s and the 1950s.
They've been georeferenced, meaning you can compare them directly to modern day maps and satellite images, with a transparency slider or side-by-side on screen. The incredible level of detail shows buildings, streets, railways, industrial premises, parkland, farms, woodland, and rivers.
You can see how an area has changed over the last 100 years — here at Londonist we can see the St Luke's Hospital which stood near here until it made way for the estate of the same name in the 1960s.
