Ever seen a brown-brick tube station with large windows? Then you've probably clocked the work of Charles Holden.
Holden (1875-1960) designed dozens of stations for London Underground, including many of architectural distinction.
His earliest designs from the mid-1920s are typified by those at the foot of the Northern line: neatly proportioned Portland stone structures with glazed screens and prominent roundels. Every station from Clapham South to Morden follows this template.
Holden's practice designed many of the outer-London stations on the Piccadilly line during the 1930s. Brown brick, huge windows, spacious and welcoming, each one is different yet clearly of a family.
We've put together the map above to show just how many stations owe their appearance to Holden.
Images: The main photos are all by the author. Those in the map are by the author or are public domain with these exceptions, all published under creative commons licence: