The state Department of Energy and Environmental Protection announced Monday that it will be participating in Connecticut’s Open House Day and welcomes visitors to state park museums free of charge on Saturday.

State parks that will be open free of charge include: Gillette Castle State Park in East Haddam; Fort Trumbull State Park in New London; Osborne Homestead Museum in Derby; and Dinosaur State Park in Rocky Hill.

Connecticut Open House Day, a popular statewide event, is sponsored by the Connecticut Office of Tourism, and is designed to broaden awareness among residents of Connecticut’s exceptional cultural and tourism assets and to encourage them to become ambassadors who share their newfound discoveries with visiting family and friends.

At the Osborne Homestead, free tours will be available from 10 a.m. to 4 p.m. Visitors may also explore the beautiful gardens surrounding the museum.

Visitors can also enjoy the Kellogg Environmental Center and participate in a free decoupage workshop from 1 to 2:30 p.m. Guests can make decoupage art honoring Francis Osborne Kellogg’s love of flowers and handicrafts. All materials, including pictures of the Kellogg Estate’s gorgeous flowers, will be supplied.

The Kellogg center and Osborne Homestead are located off Route 34 at 500 Hawthorne Avenue in Derby. Space is limited. To register, call (203) 734-2513 or send an email to: donna.kingston@ct.gov.

Free admission will also be available at Dinosaur State Park from 9 a.m. to 4:30 p.m. There will also be a “Build a LEGO Dinosaur” contest. LEGO bricks will be provided and participants must construct their dinosaur at the park from 10 a.m. to 2 p.m. Prizes will be awarded in three categories: age 5 and under, ages 6 to 10 and 11 and older. Builders will not be able to keep their creations.

Visitors will also be able to enjoy films, animal programs and guided nature walks throughout the day. The track casting and mining areas are open and anyone who wants to make a cast must bring 10 pounds of Plaster-of-Paris and ¼ cup of cooking oil. This area is open from 9 a.m. to 3:30 p.m. daily. One cast per family or group is permitted.

The mining activity is open from 9:30 a.m. to 4 p.m. and there is a materials fee. A free craft area will also be open in the Discovery Room from 11:30 a.m. to 3 p.m.

Visit the park’s Facebook page, Dinosaur State Park, Friends for information.

At Gillette Castle State Park free admission to the castle and guided hikes will be offered. Visitors will be able to have a picnic, walk on the trails, and visit the gift shop and concession stand.

Hours are 10 a.m. to 5 p.m. Staff will be on hand to answer questions about the castle.

At Fort Trumbull State Park, the visitor center will be open from 9 a.m. to 5 p.m. with free admission.

The center contains multimedia theaters, computer touch screen interactive exhibits, 3-D models and extensive graphics and text panels. The center depicts more than 225 years of military history and technological advances from the Revolutionary War to the Cold War.

Some of the main themes of the Visitor Center are the Sept. 6, 1781, attack by the British under the command of Benedict Arnold, the U-boat menace during World War II and the anti-submarine efforts during the Cold War.