The window of the Martin Luther King Jr. Library in Northwest Washington. (Jeffrey Porter/The Washington Post)

But the building, completed in 1972, is also expensive to maintain. For instance: because a specific, hard-to-find window is needed to replace any that break in the building, fixing a broken window costs $16,000.

This at a time when the library system recently proposed closing the King library on Sundays to save money .

The good news is that the 400,000-square-foot building is likely worth tens of millions of dollars. To see if that value can be leveraged while maintaining a central downtown library, officials from the D.C. Public Library system and the Downtown Business Improvement District are convening a panel of national real estate experts to spend a week studying the building and determining how best to utilize it.

About half of the city’s libraries have undergone renovations in recent years, and Ginnie Cooper, chief librarian for the District, is beginning to look at the other half, which means “we have to examine what should happen with the MLK Library building,” she said in a statement Thursday.

Architecture, planning, development, finance and library science professionals assembled by the Urban Land Institute, a non-profit research group, will convene to study the building beginning Nov. 13 and ending Nov. 18, when they will present their findings.

Library spokesman George Williams said that as long as there continues to be a central library that retains the King name, the system was open to options including sharing the building or moving to another location.

“We have to start thinking about what is best for this building,” Williams said. “What that panel is going to do is say whether the building is providing the best value. Are there ways the building could give the District more value? And how might that look?”

As the King building aged, a number of ideas came forth to preserve or expand a downtown library. Mayor Anthony Williams proposed building a new central library on the site of the former convention center, where CityCenter DC is being constructed, but the developers have outlined other plans for the property.

More recently the Federal City Council, a group of influential business leaders, floated the idea of expanding the Carnegie Building, in Mount Vernon Square, and relocating most of the central library’s functions there.

In 2006, the National Trust for Historic Preservation raised the idea of selling it Dupont Circle headquarters and moving into the King library or another historic building, but the group has not yet sold its building.

Follow Jonathan O’Connell on Twitter: @oconnellpostbiz