One of the most historic landmark buildings in Devizes – The Keep next to the former Le Marchant Barracks – goes on sale this Saturday.

Devizes-based Gaiger Brothers and its contractors have spent the past 17 months restoring the Grade II listed building in London Road.

They are converting the four-storey building into 13 apartments, including a flagship penthouse.

On Saturday, between 11am and 3pm, the first five apartments will be marketed and The Keep will be opened to the public.

Devizes estate agent Martin Walker is selling the apartments and said the interest in the building was unprecedented.

As he showed the Gazette around the property, he said: “The level of interest has been phenomenal. We haven’t advertised it at all, apart from having a board on the building, and we have a list of interested people as long as the Magna Carta.

“I think the interest in The Keep is because there is nothing like it in the town and there may not be again.”

He said that most people who expressed an interest in the apartments were owner-occupiers, those who were looking for a second home and a few who were likely to be investors.

He said the one-bedroom apartments might interest first-time buyers. There is no lift in the building and they are not aimed at the retired.

Prices for the one-bedroom apartments start from £110,000 and the two-bedroom apartments from £140,000.

The prices will be reviewed after the first five apartments are sold and Mr Walker and Gaiger Brothers have not settled the price for the penthouse apartment, which is not yet up for sale.

The penthouse has two bedrooms and two bathrooms, plus another room in one of the towers which could be used as an office or another bedroom. Outside is hardwood decking and there are views of Roundway Hill and the Devizes White Horse.

We were also shown an apartment on the other side of The Keep on the third floor which has views of the Pewsey Downs.

Features of the apartments include oak flooring, underfloor heating using a modern air sourced heat pump, fitted kitchens with integrated appliances and allocated parking spaces. The apartments will be sold on 999-year leases, each with a ground rent of £195 a year plus a monthly management charge to cover the cost of buildings insurance, lighting, maintenance of communal areas and a contribution towards the long-term upkeep and repair of the building.

Mr Walker said: “It’s wonderful to see this magnificent building sensitively restored and given a new lease of life for future generations. As you would expect from Gaiger, they have provided a very high standard of finish and specifications.”

Mr Walker said Peter Kent, architect for Gaiger Brothers, designed the apartments to have an “industrial chic finish” blending in contemporary materials with existing architectural features such as exposed brickwork, Bath stone and wooden balustrades.

Le Marchant Barracks opened in 1878 and the Wiltshire Regiment was based there until 1967. The main barracks building was redeveloped in 2007 while The Keep was privately owned until it was sold to Gaiger Brothers last year. The Keep comprised a guard room, detention cells and a garage for the barracks fire engine.

The building required major repairs and the first six months were spent on structural work before conversion could start.

Richard Phillips, site manager for Gaiger who retires after The Keep is finished, said he had enjoyed being part of the team restoring the building.

He said: “I get asked a lot about it by people when they hear I am working on it. There’s a lot of interest in it and if you drive into Devizes from the north you can’t miss it.”