National Gallery of Art Washington DC

The exterior stone work is being systematically removed, numbered,stacked and then re-attached.
According to the NGA website there are approx . 16,200 Tennessee pink marble panels that are being carefully removed and then re- attached with new supports. Each three-inch-thick panel weighs approximately 450 pounds and typically measures five feet wide by two feet high. This restoration project will not be completed till Spring 2014.
Meanwhile the Gallery is open for visitors. Go see the Harry Callahan show it is amazing.