The seventh annual Montgomery County Heritage Days will spotlight 32 historical sites from Hyattstown to Silver Spring this weekend with tours, demonstrations and special activities. Five sites, including Whites Ferry in Dickerson, have been added to the event.

Free round-trip rides across the Potomac River will be offered Saturday and Sunday on the Gen. Jubal A. Early ferry, which has been operating in Montgomery County since the 1800s.

"The ferry is one of the gateways into Montgomery County," said Peggy Erickson, executive director of the Heritage Tourism Alliance of Montgomery County, one of the sponsors of the Heritage Days. "To go from urban Bethesda to Whites Ferry and have this wilderness experience is quite amazing. It's a time machine, and you are transported back. It is not what you would expect in this county."

This year's venues are divided into seven categories, such as historical schools and educational facilities, early transportation, early Montgomery County towns, hidden treasures, African American historical sites, Civil War sites and historical agricultural sites. In previous years, the sites were divided by location.

"We thought we had enough strength in each category this year that if you were interested in a particular category, you could pick out the thing that you were interested in and go to that," Erickson said. "It's a more clear way to pick out your events."

Historical sites added for tours this year include the Gaithersburg-Washington Grove Volunteer Fire Department Museum at 13 E. Diamond Ave. in Gaithersburg, which opened last year. It features memorabilia, pictures and restored 1941 Diamond T and 1938 Seagrave firetrucks that children can sit in.

"The museum is there to protect the memory of the volunteers who served the city," said museum director Garry Walker.

The new site in the early towns category is the Davis House, 26020 Frederick Rd. in Hyattstown. Tours of the brick Federal-style house, which was built in 1812 by George Davis, will be offered.

Other historical sites open this year for the first time during the Heritage Days are the Brookeville Two-Room Schoolhouse, built in the early 19th century on North Street in Brookeville, and the Linden Farm, 20900 Martinsburg Rd. in Dickerson. The farm, which features a hog shed, dairy barn and milk house, is the most completely restored farmstead in the county.

African American historical sites include the Sandy Spring Museum, 17901 Bentley Rd. in Sandy Spring, which will feature tours of the exhibit hall and demonstrations of spinning, rope-making, basket-weaving and blacksmithing.

"When you think about the county existing in the 1700s and the incredible role it has played in history, I think that a lot people should focus on it and learn about it," Erickson said. "We want people to know the agricultural history, the ethnic history and just what historical jewels we have in this county and what fun history can be."

All Montgomery County Heritage Days events are free, and brochures of site locations are available from libraries, county recreation centers and participating groups. Most activities will be held from noon to 4 p.m. Saturday and Sunday. For more information, call 301-515-0753. A list of sites and addresses is available at www.heritagemontgomery.org.

Free round-trip rides across the Potomac River will be offered this weekend on the Gen. Jubal A. Early ferry.