There's no place like homes for the holidays. Here's a sampling of the season's open houses, free, unless otherwise noted.

* The Christian Heurich Mansion (1307 New Hampshire Ave. NW), which houses the Columbia Historical Society, will sport Victorian trappings for candlelit tours today and Saturday, 5:30 to 7:30 p.m. While you're there, take a look at the Society's latest exhibit, "Topping Our Washington Monument," a centennial celebration of the Monument on the Mall. Admission for the tour is $1. 785-2068.

* The Old Stone House, 3051 M St. NW, will be softly candlelit and open for a holiday tour this Friday, 7 to 9:30 p.m., with music provided by the Greensleeves Recorders. Regular tours of the decorated house are available daily 9:30 a.m. to 5 p.m. 426-6851.

* The Lee-Fendall House (614 Oronoco St., Alexandria) will be open daily (except Mondays), 10 to 4, through December 22. The Alexandria Council of Garden Clubs has put up a show called "A Christmas With the Lees of Virginia," with wreaths, swags, topiaries and other popular period decorations. Admission is $2 for adults, $1 for students. 548-1789.

* Victorian candlelight tours (how is Victorian candlelight different? you might ask) will be held held at Surratt House and Tavern (9110 Brandywine Road, Clinton, Maryland) Sunday, 5 to 9, and Monday and Tuesday, 6 to 9. The house will be decorated as it was in the 1860s, and members of the 33rd Virginia Company Volunteers have promised to be on hand. Admission: $1 for adults, 75 cents for senior citizens, 50 cents for students. 868-1121.

* Beginning Monday, Mount Vernon will be dolled up in traditional greens through January 6, and open for tours, 9 to 4. Admission is $4 adults, $3.50 senior citizens, $2 children. 780-2000.

* This is the first year that homes in downtown Leesburg will be opened to the public. The historic homes will be lit by candles Saturday 15, 1 to 6, and horse-drawn carriage rides will be available. Admission $6. 777-3174.

* Oxon Hill Manor, 6901 Oxon Hill Road, Oxon Hill, opens its doors Sunday, noon to 5, with continuous vocal and instrumental music of the season performed in the Georgian house. 567-1914.