It has to be the cheapest property on the market. For just £100 you can buy lot 25 at a Norwich auction – and it's not a misprint nor a mistake.

Norwich Evening News: The properties along Nene Quay in Wisbech. Pic: Archant libraryThe properties along Nene Quay in Wisbech. Pic: Archant library

But there is a drawback - you can't get in it.

What you're buying is a mysterious room in part of a historic building that no one, including the auctioneer, has managed to enter.

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In a row of historic buildings, some which date to the late 16th century, is this room sealed from both sides and with no other access.

Norwich Evening News: The William H Brown auction details showing the property for sale for £100. Pic: William H BrownThe William H Brown auction details showing the property for sale for £100. Pic: William H Brown

No one seems to know its origins or if there's anything interesting inside.

The auction details state: "This is an opportunity to acquire a flying freehold which extends over part of a vehicular access passageway and comprises a single, currently inaccessible room, measuring approximately 12 sqm.

"There is limited information and we have not, at this stage, gained access."

Victoria Reek, auction manager for William H Brown's East Anglian auction centre, selling the room in Nene Quay, Wisbech, said it was one of the most unusual lots she had ever come across.

Norwich Evening News: The mysterious room which joins two buildings and which no one, not even the auctioneer, has recently gone into but which is for sale at auction. Pic; William H BrownThe mysterious room which joins two buildings and which no one, not even the auctioneer, has recently gone into but which is for sale at auction. Pic; William H Brown

"There is no way in or out from the outside, we have been instructed to sell it and we're starting the price off at £100," she said.

"We think it would make an ideal store room for a market stall holder but it gives you no access rights, it really is just a room which at the moment, you can't get into.

"We do come across all kinds of interesting lots like this in Norfolk but this is probably one of the most unusual."

She said the room was being sold by Fenland District Council along with other parcels of land and property they have owned for years. Situated at 5-6 Nene Quay, it is between the Tasty China restaurant at number 5 and Bridge Insurance office next door.

Norwich Evening News: Victoria Reek, auction manager at William H Brown's East Anglian Auction Centre. Pic: submittedVictoria Reek, auction manager at William H Brown's East Anglian Auction Centre. Pic: submitted

A 'flying freehold' means it has no structure underneath but extends over a passageway.

Flying freeholds are most common where an older, large building has been converted into a number of smaller properties. At some point the room may have belonged to the building next door but somehow got separated over time.

Historic documents show the buildings along Nene Quay were originally shops and granaries, timber-framed and jettied with the upper floor built protruding from the lower floor.

The auction takes place on February 20 at Dunston Hall Hotel in Norwich at 11.30am.

Norwich Evening News: For sale for just £100. The mysterious closed off room seen from the front, which is for sale at auction. No one has entered the room. Pic: William H Brown.For sale for just £100. The mysterious closed off room seen from the front, which is for sale at auction. No one has entered the room. Pic: William H Brown.