Most beachgoers are content to leave their brains on the Bay Bridge, as the saying goes. But in case of rain or severe sunburn, here are some museum and gallery retreats: BURTON-INGRAM HOUSE -- Lewes, Third and Shipcarpenter Streets. Constructed of hand-hewn timbers and cypress singles with cellar walls of sailing ballast, stones and brick. Restored by Lewes Historical Society, 302/645-8346. Free. Hours vary, generally 10:30 to 3. CANNONBALL HOUSE MARINE MUSEUM -- Lewes, Front and Bank Streets. Erected before 1797, it was hit with a cannonball during the War of 1812 and now holds marine artifacts. Hours vary, generally 10:30 to 3. Lewes Historical Society, 302/645-8346. CHESAPEAKE BAY MARITIME MUSEUM -- Navy Point, St. Michaels. Small-boat types, crabbing skiffs, the last logbottom bugeye, skipjack, modern version of a Bay buy boat, Screwpile lighthouse, aquarium (turtles and crabs to eels). Early Baltimore clipper to modern workboats. Extensive collection of waterfowl decoys, stuffed birds. Working boat shop now restoring a 1914 Herreschoff sloop. Gift shop. Daily, 10-5, through January. Adults $2.50; under 12, $1. 301/745-2916. DE VRIES MONUMENT AND FORT SITE -- Pilottown Road, Lewes. On the site of a fort built in 1631 by De Vries and 28 Dutch settlers, the original establishment of Lewes, the first settlement in Delaware. (The following spring, Indians burned the stockade and massacred the population.) DOCTORS OFFICE -- Market and Front Streets, Lewes. Built by Dr. David Hall about 1850, the Greek Revival house now stands as a museum showing a turn-of-the-century doctor's office. Free. Hours vary. Lewes Historical Society, 302/645-8346. ANNA HAZZARD MUSEUM -- 11 Christian Street, Rehoboth. Open weekends, 1-4, through Labor Day. Original "camp meeting" house dating to the turn of the century. Photos of early Rehoboth. Current display, "Early Office Furniture." Free. 302/227-2974. LEWES TOURS -- 90-minute walking tours of late 17th- and early 18th-century buildings at 10:30 a.m. Tuesdays, Thursdays, Fridays and Saturdays. Meet at Thompson Country Store, Historic Complex, Third and Shipcarpenter Street. $2 adults, children under 12 free. (Covers all of the Lewes sites mentioned here and the Early Plank House, the Lightship, Maull House, Lewes Presbyterian Church, Saint Peter's Episcopal Church, Rabbit's Ferry House and Ryves Holt House.) 302/645-8719. MARVEL GALLERY -- Canal Square, Lewes. Lithographs, etchings by internationally known artists including Picasso, Renoir, Miro, Chagall. Daily 10-4. 302/645-2628. OCEAN CITY LIFE-SAVING STATION MUSEUM -- Boardwalk at Inlet. Building used from 1878 to 1962 to house the U.S. Life-Saving Service and the Coast Guard. Antique bathing suits, dollhouse models of the resort's older hotels, artifacts from sunken ships, shells, two 250-gallon saltwater aquaria with a variety of fish, crabs and mollusks. Hand-carved decoys and a large collection of life-saving equipment. Adults $1, children 50 cents. 11 to 10 through the summer. 301/289-4991. JULIA PURNELL MUSEUM -- 208 W. Market Street, Snow Hill, Maryland, 45 minutes south of Ocean City. Worcester County history, early farm tools and kitchen equipment, looms, costumes, uniforms, Indian artifacts. Adults $1, 12 and under free. Monday- Friday, 10-4; Saturday-Sunday, 1-5. 301/632-0515. REHOBOTH ART LEAGUE -- Dodds Lane, Henlopen Acres, Rehoboth. Crafts and decorative arts, through Wednesday. Daily, 10-4. 302/227- 8408. SCHROEDER GALLERY -- Canal Square, Lewes. Watercolors and prints by Howard Schroeder. Daily 10-4. 302/645-8094 ZWAANENDAEL MUSEUM Lewes, Kings Highway and Savannah Road. A replica of the town hall in Hoorn, Netherlands, 1631, erected to commemorate the 300th anniversary of the first Dutch settlement in Delaware. Artifacts of historic Lewes and lower Deleware, military and maritime exhibits. Voluntary donation. Tuesday-Saturday, 10-4:31; Sunday 1:30-4:30. 302/645-9418.