When PNC Financial Services Group Inc. bought Riggs National Corp., it also bought some of the District's best-known historic commercial real estate properties.

Most famous is the Riggs branch on the 1500 block of Pennsylvania Avenue NW, across from the Treasury and the White House. The building, a classical revivalist white granite structure with ionic columns, was built in 1899. It is on the National Register of Historic Places.

Riggs's Mount Pleasant branch, at the corner of 14th Street and Park Road NW, is the only other Riggs structure on the National Register. Several other well-known Riggs branches, such as the landmark 1922 former headquarters of Farmers & Mechanics National Bank at the corner of Wisconsin Avenue and M Street NW in Georgetown, are in historic districts.

Since Joe L. Allbritton bought control of the bank in 1981, Riggs has lavished attention on each of these branches, spending millions on preservation efforts. It restored its 1503 Pennsylvania Ave. branch in 1986 and named it after the bank's founder, William W. Corcoran. Although historic and grand, many of these banks lack some modern touches. For example, the Corcoran branch has no easy parking and has had only limited pedestrian access in recent years, because of the reconstruction of Pennsylvania Avenue in front of the White House.

Brian Goerke, a spokesman for PNC, said the company will initially operate all 51 Riggs branches. Long-term decisions about historic structures such as the Corcoran branch, which area bankers have said would be nearly impossible to operate profitably, have not been made, he said.

Ellen McCarthy, D.C.'s deputy director for development review and coordination of planning, which oversees the District's historic preservation efforts, said PNC would probably be able to change the signage on these buildings, as long as it goes through the approval process and does not change the character of the exterior.

-- Terence O'Hara

The Riggs branches on Pennsylvania Avenue, above, and in Georgetown, left, are some of the District's most notable commercial buildings.