The Artery Organization broke ground recently for a 10-story, 175-unit rental apartment building for the elderly in Gaithersburg called Forest Oak Towers. The Department of Housing and Urban Development is funding the project under FHA 221 (d) (4) guidelines, with rental subsidy assistance for occupants under the FHA Section 8 program. The building on Oden 'Hal Avenue is expected to be finished in March 1982.

William S. Harps of Washington has been installed as president of the American Institute of Real Estate Appraisers. A former president of the Washington Board of Realtors, Harps is the first black president of the AIREA, an affiliate of the National Association of Realtors. He is first vice president of John R. Pinkett Inc.

PasJohn Investments, a Colorado-based investment group, has purchased the 347-unit Quebec Arms apartment project near Langley Park for nearly $4 million. Coldwell Banker represented the purchaser and Monivale Venture, the seller.

The Poretsky & Starr building firm has started construction of a 100,000-square-foot, low-rise office building called Courthouse Plaza II in central Fairfax City.

The City of Alexandria will sponsor seminar on the city's advantages for Northern Virginia Realtors. The program will be held the morning of Dec. 3 in the Ramada Inn in Old Town.

Linpro, a development firm based in Georgetown, has purchased nine acres of commercial land at Wiehle Avenue and Sunset Hills Road in Reston and will build two three-story office buildings.

Alan Glen Inc. is building three large houses in the 2300-block of L Street NW, north of Washington Circle. The houses, which are being marketed by Bonnie B. Foster Real Estate, will range in price from $239,500 to $275,000.

Ryan Homes, the largest-volume homebuilder in this area, has opened its first garden condominium subdivision in Frederick, Md. Called Ambertowne, the project wil include two-bedroom apartments starting from $33,900.