Maridon Museum, 322 N. McKean St., is open 11 a.m. to 4 p.m. Wednesdays through Saturdays. Admission is $4 for adults, $3 for senior citizens and students, and free for children younger than 8. Guided tours are available with advance notice for no extra charge. Call 724-282-0123 or visit www.maridon.org.

Filmmakers Galleries, 477 Melwood Ave., presents the Marcellus Shale Documentary Project, with work from six photographers, through Sunday. Hours are noon to 7 p.m. Mondays through Thursdays and noon to 6 p.m. Fridays. E-mail info@the-msdp.us.Carnegie Museum of Art, 4400 Forbes Ave., displays seven, 20-foot trees flanking the museum’s perennial favorite, the Neapolitan presepio, an 18th-century Nativity, through Sunday. Each tree is decorated in the theme of world’s fairs, celebrating the exhibit “Inventing the Modern World: Decorative Arts at the World’s Fairs, 1851–1939” now on view in the Heinz Galleries of the museum. Hours are 10 a.m. to 5 p.m. Tuesdays through Saturdays, with additional hours until 8 p.m. Thursdays, and noon to 5 p.m. Sundays. Admission is $17.95 for adults, $14.95 for senior citizens, $11.95 for students with ID and children ages 3 to 18, and free for children younger than 3. Call 412-622-3131 or visit www.cmoa.org.