Colliers’ Hotel Agency have announced that anyone wishing to purchase No Man’s Fort, which is off the coast of the city, must submit a bid by next Friday (November 26).
It comes as the price has been slashed by over £600,000 to £3.6m.
The original asking price was £4.25m.
No Man’s Fort is a 23-bedroom luxury island retreat, it was refurbished in 2015 and a spa, restaurants, helipad, and events space were added.
More recently additional landing stages and new generators have been installed, as well as the fort’s own pub.
MORE: One of the Solent Forts has been sold - here's how much for, Who is Mike Clare, the man selling three Solent Forts?
Have a look at some pictures from inside No Man’s Fort in our gallery below.
Paul Barrasford from Colliers’ Hotel Agency said: 'Following our recent sale of Horse Sand Fort, Mr Clare is keen to progress on No Man’s Fort and has reduced the asking price to £3.6m and set a deadline for offers to come forward.
‘There are not many people who can say that they own a fort, this site could be an amazing addition to a property portfolio, whether it is used as a hotel as it is now, a holiday residence or converted into a different use.
‘For a creative investor it could be many uses such as a data centre, specialist athletic training venue, a filming location, or even a headquarters for a fast-growing start-up. Its remote location offers the ultimate privacy and security.’
Horse Bank Fort was recently sold for £715,000 and a third fort is also up for sale – however this is available under separate negotiation.