They are a hidden gem of Norwich's history and they lurk beneath the facades of everyday buildings.
Norwich is home to around 70 surviving medieval undercrofts – more than any other town or city in the country.
And Terry George has made it his mission to photograph as many as he can. Mr George, of Portersfield Road, Norwich, has visited the subterranean storage rooms of about 40 buildings and has his sights set on continuing his journey.
The 65-year-old said: 'I started photographing undercrofts in September 2012, but it was only in February last year that I started my quest in earnest and started to visit ones that are never open to the public.
'I have got into local history over the past few years and going to the Heritage Open Days has really got me into it.'
Once the father-of-two set himself the challenge, he started compiling a list of buildings with undercrofts taken from the English Heritage List of Buildings website.
Mr George then contacted Norwich HEART who helped him add a few more.
He said only 10 of the undercrofts in Norwich are open to the public.
Mr George, who lives with his wife Elaine, added: 'It's a question of knocking on doors.'
He said not everyone understands his quest and, when he comes round to ask if he can look at someone's undercroft, he can be met with a strange look and a slammed door.
He added: 'It's just a question of plucking up the courage.
'Most people have been fairly cooperative.'
Most of the subterranean gems are on the south bank of the river Wensum, taking advantage of hillside sites.
Mr George added his son Alex enjoys urban exploring and his other son Scott plays in a band Project Multivitamin, which has performed at The Crypt, the undercroft of Bedfords bar and restaurant in Bedford Street, Norwich.
• are you involved in a local history project? email sophie.biddle@archant.co.uk
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