11 a.m. -- Donaldson Run Walkabout, leaving from Taylor Elementary School, 2600 N. Stuart St.; on-site parking available. Highlights include Taylor Elementary School, heated and cooled with geothermal energy; Donaldson Run, home to Arlington's first large- scale natural stream restoration project; and Beechwood Circle, where homes from the 1930s are nestled among towering beeches.

1 p.m. -- Ashton Heights Walkabout, leaving from the Arlington Arts Center, 3550 Wilson Blvd.; limited parking available at the arts center; easily accessible from the Virginia Square Metro station. [Jay Fisette] will lead this walk. Highlights include the renovated Arlington Arts Center, the historic Woman's Club of Ashton Heights, Arlington Preservation Award-winning Four Square house, and Fisette's home.

Pay by mail by sending to Arlington County Treasurer's Office, 2100 Clarendon Blvd., Suite 201, Arlington, VA 22201. Make checks and money orders payable to Arlington County Treasurer.