The multimillion pound transformation of four floors of the Corn Exchange into a swanky hotel is set to start.

A year after the former trading floor of the historic building was turned into a dining destination with 17 food outlets moving in, work on the hotel on the second to fifth floors is getting underway.

The final phase of the Corn Exchange’s £30m overhaul boasts a 114 bedroom apartment-style hotel on the four upper floors operated by Roomzzz - which also owns a large hotel on the corner of Princess Street and Portland Street.

The hotel will include three large penthouse rooms, one of which will have access to the building’s distinctive turret that will be accessed by a private spiral staircase.

The work will also involve re-opening the original grand main entrance to the Exchange, which fronts onto Hanging Ditch and has been closed for many years, plus a hotel atrium providing access to the upper floors.

Aviva, owners of the Grade II listed building, have worked with developer Queensberry Real Estate and 5plus Architects to give the iconic three-sided building - famous for its lavishly domed ceiling - a new life.

5plus associate director Rhys Westacott, said the building had been a unique challenge: “Corn Exchange is a very complex building – there are seven (now five) different levels and 13 separate staircases – and the challenge has been to make best use of the space while preserving its unique character," he said.

Fortunately, many of the original features of the building had survived the Exchange’s many changes of use over the decades, including staircases, tiling, and marble decoration.

In fact, fireplaces installed in rooms from an earlier 40-bed hotel at Cathedral corner, called The Exchange Hotel, had even stayed in place during its time as offices.