Work has started on a US$28m (£15m, 22m euro) expansion of the Museum of the City of New York in Harlem.

The revamp was designed by Polshek Partnership Architects and features a 23,000sq ft (2,125sq m) new gallery – as well as a new lobby, curatorial centre and climate-controlled collection spaces. US$17m (£9m, 13m euro) of the cost will come from the Mayor’s Office and the City Council, with the rest of the funding coming from private donors.

Mayor Bloomberg, who attended the groundbreaking ceremony on 2 August, said: “Today marks a major milestone for this important institution that has, in recent years, succeeded in attracting new and diverse audiences and enriching the museum’s connection to its vibrant Harlem community.”

The museum’s chair, Newton Merrill, added: “This groundbreaking will begin the work that is long overdue and bring the museum into the 21st century. The addition will enable us to better protect and house our collections while providing a brilliant new gallery for public exhibitions.”

The expansion, scheduled to finish in 2008, is the first phase of a US$70m (£37m, 55m euro) overall modernisation programme that will be completed in 2012.

The museum will remain open to the public through out the construction process. Details: www.nyc.gov/mayor