Work is underway to turn the rundown St James House into a business hub.
The arches – a hotspot for antisocial behaviour – are being closed up as workmen board up windows.
The building will be given a £1.5million makeover to attract small businesses back into Grimsby town centre.
Social enterprise E-factor has taken over the building after North East Lincolnshire Council allocated the Towns Funding for the project.
The arches will be closed to become shops, cafés and workshops, which would make pedestrians in the area feel safer.
The upper floors will be turned into office space.
Its hoped this would convince businesses to move premises into the town centre and generate more footfall.
The long-awaited plans have been on the cards for more than three years, and come after a £1.8million regeneration of the wider St James Square last year.
Council leader Councillor Philip Jackson said when Cabinet approved the plans that the regeneration would help other businesses in the area.
“St James House has been run down for many years, and with the success of the Wilkin Chapman building on Cartergate and the redevelopment of St James Square, a key heritage asset in the town, the next step was to deal with the redundant building in a way that can increase footfall in the town centre and provide benefit to other local businesses,” he said.
“I’m delighted E-Factor has put forward these proposals, which bring a new dimension to St James Square, a fantastic heritage asset in our town centre. We are extremely pleased to support this scheme.”
Mark Webb, managing director of E-Factor, said at the time: “We’re absolutely delighted that our investment proposals have been received so well. We recognise that this building has been empty and deteriorating for over a decade and with our investment, supported by the Towns Fund, we are confident we can bring it back to life.
“We’re planning to purchase and redevelop the building to provide quality business accommodation for a variety of local businesses and entrepreneurs, there will also be space for small business events/exhibitions as well as workshops to support local business people.
“As an independent ‘not for profit’ company, dedicated to supporting the huge contribution local business owners make to this town, E-Factor will once again be providing wrap around business support, easy-in easy-out terms and all the guidance we can give to help create and grow successful local businesses.
“The more people who do business in the town centre, the better it will be for shops and restaurants also located there.”