Historic England is looking for photos of the country's first mosque set up in Liverpool in 1887 by English Muslim convert Abdullah Quilliam.
The Gloucestershire site of the first smallpox vaccination by Edward Jenner is also on a list of 21 places that require updated details.
Historic England said it wanted people to help "unlock the secrets".
"We want people and community groups across England to share their knowledge and pictures, so we can record important facts about places," it said.
The organisation curates the official list of England's 400,000 most significant historic places and items for the Department for Culture, Media and Sport.
Roger Bowdler, director of listing at Historic England, said: "Many buildings on the list are well-known and even world-famous. But in some cases there is much that remains unknown."
Details and photos are also being requested on:
People are being asked to "chronicle the nation's missing history" by sharing details of key sites.