Fulton County and Alpharetta celebrated the opening of a new $24.7 million library Thursday, a landmark in the development of the city’s downtown.

The 25,000-square-foot library is a centerpiece of Alpharetta’s efforts to create a walkable downtown. It will join a new City Hall and park that have already been built. Nearby retail, office and residential development are on the way.

It’s also the sixth of eight new libraries built with a $275 million bond approved by Fulton County voters in 2008.

“Today is a great day for Fulton County,” County Commissioner Liz Hausmann told about 300 people who attended the opening. “But it’s also a great day for the future of Alpharetta.”

It’s been a big month for new libraries in Fulton County. The Northwest Library in Atlanta and the Milton Library opened their doors earlier in July. Still to come: new Metropolitan and Southeast Atlanta branches, adding to the state’s largest library system.

Two other libraries are being expanded, and others will be renovated beginning next year.

Voters approved the building binge at the beginning of the Great Recession, and for a while it was unclear how the county would pay to operate the new libraries as they opened. For much of last year, one answer was reduced hours, staffing and programming at the county’s 33 libraries.

The county restored hours after commissioners approved a 17 percent property tax increase they said benefited libraries and other programs.

Earlier this month, commissioners rolled back part of that tax increase, leaving a $74 million hole in next year’s general fund budget. But county officials have said library hours will not be affected as Fulton tries to balance its budget.

Those issues were set aside Thursday as political leaders celebrated a partnership between the city and county that made the Alpharetta branch possible.

The city donated the land for the library.“It’s not just something the county does next to something the city does,” Mayor David Belle Isle said. “It’s something we both do to serve the same citizens.”

Alpharetta also has invested $30 million in the new city hall, a parking deck and other facilities.

Next month, the City Council will consider selling land nearby for a commercial development. Belle Isle said the new downtown should be fully developed in the next two years.