Work on a giant sky bar will start in a matter of days as a four-star hotel above Birmingham's Five Ways Shopping Centre begins to take shape.

Steelwork for a cocktail bar and restaurant overlooking the city on the 16th storey of the new Park Regis Hotel will be craned into place.

The work forms part of one of the largest urban regeneration schemes in the city for years, with the old Auchinleck House office block being transformed into a four-star hotel with a giant lobby and plans for a 50,000 sq ft conference centre.

Phil Carlin, managing director of Seven Capital, the firm behind the renovation, which is also developing the Harrison Drape building in Digbeth, Britannia House on Great Charles Street and the Kettleworks in the Jewellery Quarter, said it would compete with the best of Birmingham's hotels.

He said: "We are pitching this at the same quality that you can get anywhere else in the city. The Hyatt and Hotel Du Vin are four-star and the idea is we are challenging them.

"It is a gateway to the city and one of the largest sites of single ownership in a prominent location anywhere in the city centre."

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He added: "This is one of the biggest urban regeneration sites in Birmingham, at two-and-a-half acres.

"It is comparable to the Snowhill development when you think it means changes for four different streets. There is a lot of money going into resurfacing and improving the public realm."

The creation of the sky bar represents a milestone in the scheme which is set to complete in October 2015.

Seven Capital bought the 2.3-acre site from LaSalle Investment Management in 2011 and is turning the office buildings into a 253-room hotel to be run by StayWell Hospitality Group.

The firm has already sold the scheme for £48.5 million. It also has consent for a 250,000 sq ft conference centre in a second phase of work but until then the plot will serve as a 144-space car park.

Mr Carlin said he thought the new sky bar would turn heads as there was little to compare other than Marco Pierre White's at The Cube.

"It draws comparisons with Marco's, which is the only real competitor but we think it is different as that is a mixed-use building," he said.

"This will be a complete experience, from dropping your car off, through the reception area to the sky bar."

He added: "We are able to offer a real sense of arrival because of the space we have. People will be able to turn up, throw their keys to the concierge and go about their business."

The work will see an additional floor added to the building which was constructed between 1958 and 1961.

The 15th floor will house a private dining area which can split into eight or seat up to 250 people and is aimed at the corporate market as well as weddings and other events.

It will also have a lobby lounge and bar, library, business centre and gym.

Andy Robinson, development director at Seven Capital, said the scale of the development would make it a natural meeting place for businesspeople in the city.

He said: "It is a very large reception area which will be a central meeting point for a sales meeting or interview, and somebody coming from out of town doesn't have to struggle to find it - it's an easy journey in and out."