Most are maintained by nonprofit organizations; fees are tax-deductible.

Audubon Naturalist Society, 8940 Jones Mill Rd., Chevy Chase--40-acre estate with renovated house. House and grounds available for 8 hours. No air conditioning. Must be catered by Ridgewells. $700. 652-5964.

Boyhood Home of Robert E. Lee, 607 Oronoco St., Alexandria--Brick townhouse with large grassy gardens and flagstone patio. Limited to 100 people. Soft music outside (no amplifiers or brass). No dancing inside the house. $100 per hour; $100 extra for use of dining room. 548-8454.

Brookside Gardens, 1500 Glenallan Ave., Wheaton--Public garden with 50 acres of landscaped flowers and plants. Gazebo available for ceremonies only. Weekends 10:30-11:30. No receptions. $75, refunded if it rains. 949-8231.

Cabells Mill, Centreville, Va. (Fairfax County)--Renovated inn, built around 1820. Adjacent grounds also available. Building capacity 150 people, available 8 a.m. to midnight. Mill, $225; grounds, $175 for 4 hours to county residents. Extra for nonresidents and for additional hours. 631-9566.

Carlyle House, 121 N. Fairfax St., Alexandria--Built in 1752, historic building with outside patio and formal gardens. (No dancing inside, no amplified music outside.) Available after 6 p.m. Standing wedding inside, rented chairs allowed outside. Air conditioned. $600. 549-2997.

Collingwood Library and Museum, 8301 East Boulevard Dr., Alexandria--One of the homes on George Washington's River Estate overlooking the Potomac; large rooms with hardwood floors; extensive grassy grounds and flagstone patio. Cost $200-300; wine, beer, punch only, no kitchen facilities. 765-1652.

Colvin Run Mill, 10017 Colvin Run Rd., Great Falls, Va.--Renovated grist mill available from 5 p.m. to midnight. Can hold 150 people in two floors. Garden adjacent to mill also can be rented. Mill, $200 for 4 hours; garden, $150. 759-2771.

Decatur House, 748 Jackson Place, NW.--19th-century townhouse on Lafayette Square near the White House. Inside can seat 40; 80 standing. Courtyard available for outdoor functions with the use of a tent. $1,500 for 4 hours. 673-4273.

Green Spring Farm, 4601 Green Spring Rd., Alexandria.--Farm is attached to art gallery. Inside facilities hold up to 40 people, air conditioned. Grounds with lawns and duckpond, will hold 300 people. Weekends only. Full kitchen facilities and piano available. Four hours rental. House, $200; grounds, $150; $20 per additional hour. 941-6066.

Lee Fendall House, 429 N. Washington St., Alexandria.--Beautiful historic home with large garden. 100 capacity in house, 125 if canopy used in garden. No amplified music. No dancing inside house. $75 per hour for use of house and/or garden. 548-1789.

McCrillis Gardens and Greentree Estate--Private home donated to Montgomery County Park and Planning Commission. House accommodates 50 people. 5 acres of flower gardens will hold 100 people. Tent required. Kitchen facilities. No hard liquor. 10 a.m.-7 p.m. $350 for 4 hours. Weekends only. 949-8230.

Montpelier Mansion, Laurel, Md.--18th-century Georgian mansion located on 25 acres. House and grounds available for weddings and receptions. No dancing or amplified music. Alcoholic beverages permitted. Fee for 56-100 guests: $350 for 6 hrs., county residents; $500, non-county residents. 779-2011.

Old Stone House, 3051 M St. NW--Oldest building in Washington, located in Georgetown. Gardens behind house available for wedding ceremonies only. Limited to a small number of attendees. Free. 426-6851.

Rockville Civic Center Mansion, 603 Edmonston Dr., Rockville--Restored air-conditioned mansion built in the 18th century. Ballroom available for dancing inside. Rose gardens outside. $350 for residents, $550 to others. 424-3184.

Sully Plantation, Route 28, Chantilly, Va.--Restored Lee family house near Dulles Airport. Grounds only available for weddings and reception, with use of a rented tent. $150 for 4 hours. 437-1794.

Textile Museum, 2320 "S" St. NW--Historic house in Kalorama often booked for weddings. Formal garden available; dancing allowed only inside on marble foyer. Room for 120-150 people standing inside museum. No air conditioning. $600 for 5 hours after 5 p.m. 667-0441.

Woodlawn Plantation, Mt. Vernon, Va.--One of several museums owned by the National Trust for Historic Preservation, whose policy is not to allow weddings, only receptions. Beautiful house and formal gardens. Use of garden necessitates rental of tent. Dancing allowed with rented dance floor outside only. $700 after 5 p.m. 557-7881.

Woodrow Wilson House, 2340 "S" St. NW.--Large red-brick townhouse near Dupont Circle. Interior of house and terrace limited to 80 people. Garden can be used for up to 200 with rented tent. No wedding ceremonies allowed. Dancing prohibited in house. $1,000-2,000. 387-4062. Public Inns, Restaurants, Hotels

Most do not charge for rooms or space used; costs usually figured on the food and alcohol served. Reduced rates on rooms for guests often available, and in some cases bride and groom given a complimentary honeymoon suite for the wedding night.

Anchorage House, 603 Queen St., Alexandria.--Beautiful house with larger terrace and garden. Food must be bought from the house; liquor brought in by patron. Dancing inside or out, but no brass instruments, drums or amplified music allowed. $300 plus $5 per person for 3 hours. 683-3705.

Cedar Knoll Inn, George Washington Memorial Pkwy., Mt. Vernon, Va.--Built in 1854 on George Washington River Estate. Outdoor-terrace view of Potomac River. Dancing and music inside or out. Minimum: $1,200 for food and use of rooms. 360-7880.

Evans Farm Inn, 1696 Chain Bridge Rd., McLean.--Reconstruction of 18th-century Virginia plantation. Located on 40 acres with small patio and gardens available. 56-8000.

Gadsby's Tavern, 138 N. Royal, Alexandria--Historic structure dates back to 18th century. Outdoor terrace, as well as indoor rooms. 548-1288.

Normandy Farms Inn, 10710 Falls Rd., Potomac, Md.--Newly reopened turn-of-the-century inn. Outdoor terrace soon to open. 983-8838.

Old Angler's Inn, 10801 MacArthur Blvd., Potomac, Md.--Upper limit of 30-40. Outdoor flagstone patio with fountain. Beautiful tall trees provide shade. 365-2425.

Red Fox Inn, Route 50, Middleburg, Va.--Established in early 1700s, beautiful restored inn and restaurant. Outdoor garden and terrace available. Terrace accomodates 125, the second floor 100 (if dining room, use of food service required) house flowers available. 471-4455.

Sheraton Carlton, 16th and K Sts., NW.--One of the most elegant hotels in Washington with outdoor terrace available for weddings and receptions (except Sunday before 4 p.m. when brunch is served.) Large indoor rooms also available. 638-2626.

Washington Hotel, Pennsylvania Ave. and 15th St. NW.--Complete roof terrace of hotel available for receptions until 3 p.m. Afterwards, use of terrace limited to the northern side (about one-quarter of the terrace) with an indoor room nearby. Terrace overlooks White House, Washington Monument and Lincoln Memorial. Permanent canopy for rainy weather. 638-5900. Boat Cruises on the Potomac

Washington Boat Lines, Inc. 6th Ave. and Water St. SW.--Ambassador, $1,200 boat rental for 3 hours. $9 per person open bar. 554-8011.

Potomac Party Cruises, Zero Prince St., Old Town, Alexandria--"Dandy":Luncheon and dinner sailing down the Potomac. Set price per person for 3 hours; $500 for each extra hour. Air conditioned. Dance floor, speaker system. "Marianne": Smaller boat, only cold food allowed on board; holds up to 50 people. $75 for bartender and setups. $150 hour. 683-6076.

Other historic and picturesque spots available for receptions, but farther outside of Washington:

Old South Mountain Inn, Boonsboro, Md. (301--432-6155).

Gabriels, Ijamsville, Md. (301--865-5500).

Belle Grove, Middletown, Va. (703--869-2028).

Oatlands, Leesburg, Va. (703--777-3174).

William Paca House, Annapolis, Md. (301--263-5553).