There may or may not be a Great Pumpkin, but there is definitely a great pumpkin fort -- and it opens Saturday at Reston Farm Market, 10800 Baron Cameron Ave. in Reston. Constructed of a hundred tons of pumpkins supported by cinderblock, wood and hay, the fort offers kids a chance to climb, bob for apples, ride ponies and visit a Sioux tepee for face-painting ($1; the other activities are free). Grownups meanwhile can peruse the pumpkins, apples, pies, cider and honey for sale. Open 9 to 8 daily through October. 759-7272.


It's back to the simple life at the Oxon Hill Farm Fall Festival 10 to 4 Saturday with demonstrations on blacksmithing, wheat-weaving and woodcrafting. Visitors can help with the applebutter- , syrup- and ice-cream-making or sample the finished products while listening to the Bluegrass Tradition and other musical groups. Free. Take I-95 to exit 3A (Indian Head Highway) south and follow the signs. 839-1177.

Takoma Park's seventh annual Old Town Street Festival fills Carroll Avenue and Willow Street 11 to 6 Sunday with 20 bands and vocalists (including Chicano folklorist Rudy Arredondo and bluegrass group Sprouts of Grass) and more. There'll be face-painting, parachute games and kids' theater, and about 200 vendors will sell everything from handmade crafts and imports to Chilean and Vietnamese foods. Free. Take Metro's Red Line to Takoma. 270-1701.

On that note, Frederick's seven-block-long "In the Street" party opens at 10 Saturday with a mile run (register at 9) and continues with scores of local musicians (including saxophonist Deanna Bogart), skateboarding and free-style biking demos and a children's area with puppet shows, pinåatas and more. Free, along Market Street. 301/694-1436 or 301/694-1440.

Hundreds of crafters gather on Main Street and University Drive in Fairfax for the city's 11th annual Fall Festival 10 to 5 Saturday: Goods for sale include Christmas ornaments, leather and jewlery, and there'll be music by one-man band Bob Devlin, the La Dee Dahs and others. For kids: scarecrow-making, face-painting, a petting zoo and more. Ethnic, country-style and seafood dishes for sale. Free. 385-7858.


The gardens and grounds of the White House will be open 2 to 5 Saturday and Sunday for the annual fall tour that includes the Jacqueline Kennedy, Rose and Children's gardens and the 135-year-old John Quincy Adams American Elm. It's free, and the Park Service promises that any visitor in line by 5 can make the tour. Call 485-9666 between 9 and 4 or 485-PARK . . . the Victorian Craft Fair at the Surratt House and Tavern (9110 Brandywine Rd. in Clinton) is 12 to 4 Saturday and Sunday. 868-1121 . . . the U.S. Sailboat Show packs Annapolis Harbor this weekend with more than 500 boats. There's more about it on page 68 . . . the 10th annual convention of American Kite Flyers winds up 10 to 5 Saturday with stunt and free-flying and comprehensive competitions at the Loudoun campus of Northern Virginia Community College. Free. Call 424-6976.


At the "Deco to '50s Show" at the Hyatt Regency Hotel (2799 Jefferson Davis Hwy.) 11 to 7 Sunday in Crystal City. More than 70 dealers will have everything from silver cocktail shakers to swanky neon for sale. Part of the proceeds benefit D.C.'s Gift of Peace AIDS Clinic. It's $4. Call 369-6776.

Thousands of collectibles, new, used and children's books will be for sale at the Latin American Book Fair 6 to 9 Friday and 10 to 9 Saturday and Sunday at the University of the District of Columbia (Building 41 on the Van Ness campus). The free event opens with a talk at 6 Friday by Mexican author Carlos Fuentes. (For related free films, see Film Notes on page 31.) 282-7538.


More than a hundred riders and horses will give it their best at the 20th annual National Jousting Championship 11 to 5:30 Sunday on the Mall (at 17th and Pennsylvania). On hand (and hoof) will be six-time champion Mike Virts and his appaloosa Missey. Free. Call 804/933-8221.

Meanwhile, the International John F. Kennedy Memorial Field Hockey Tournament is 8:30 to 5:30 Saturday and Sunday beside the Reflecting Pool near the Lincoln Memorial. More than 30 men's and women's teams from the U.S. and seven countries battle for the top title. Free. 362-8865.


It's been four years since the Old Post Office Pavilion reopened as a Place to Be; celebrate the anniversary from noon to 4 Saturday, noon to 6 Sunday and 1 to 7 Monday. Events include the Town Clowns at noon Saturday, mime Mark Jaster at noon Sunday and a special appearance between 4 and 5 Sunday by TV canine celebrity Spuds MacKenzie. Free. For a schedule, call 289-4224.


Celebrate fall at the "Autumn Glory Festival" 9 to 9 Friday and Saturday and 10 to 6 Sunday in Oakland, Maryland (off U.S. 48, 40 miles west of Frostburg). Throughout there'll be bluegrass concerts, craft and fine art sales. Saturday's the big day: A "Mountainmen Competition" at 10, (with black-powder gun-shooting and skillet-throwing), a parade with bands, clowns and floats beginning downtown at 1 and the "Official" Maryland State five-string banjo and fiddle championships at 7 ($6). Admission is free. 301/334-1948.

Front Royal's Festival of Leaves is 9 to 5 Saturday and noon to 5 Sunday. After a 5K fun run at 9 Saturday (register at 8), there'll be 75 craft artists, an antique show and sale, plus hot air balloon rides between 4 and 6 Saturday. Free; off I-66, 70 miles west of Washington. Call 703/636-1446.


Downtown abounds with the culture and color of the 76th Independence Day of the Republic of China 1 to 5 Sunday. The Taiwanese celebrations fill H Street between Fifth and Ninth NW in Chinatown with a parade (at 1), dragon performances, kung fu demonstrations, lion and folk dances and firecrackers. Free. Call 273-7510.