The Butler Ghost Walk will be held at 7:30 p.m. Friday and Saturday and Oct. 30 and 31 beginning in Diamond Park. On the 60-minute guided walking tour, participants will hear about the ghosts from Butler's historic past through tour guide Bill May's stories of Sam Mohawk, Ghosts of the Old Hospital, The Haunted Elevator, The Chinese Laundry Murder, and the Phantom Civil War Regiment, among others. Reservations are required and can be made by calling 724-256-9026 or sending e-mail to butlerghostwalk@gmail.com. Cost is $10 per person. All children under 18 must be accompanied by an adult.

Butler County Historical Society's Senator Walter Lowrie House Museum isclosed for October to set up a Civil War in Pennsylvania exhibit. Call 724-283-8116 or visit www.butlerhistory.com.

The Old Stone House hosts its “Spooky Stories” Halloween festivities from 5:30 to 8:30 p.m. today and Friday. This year's program features storytelling by Joanna Demarest, Alan Irvine, and Marsha Wong. The program tonight will include the annual costume contest for children 10 and younger. Festivities also include historical re-enactments. Admission is $5 for adults and $3 for children, but no more than $15 for a family. The Old Stone House at the intersection of Routes 8, 173 and 528 is owned and managed by Slippery Rock University. Call 724-738-2409 or visit www.oldstonehousePA.org.

Harmony Museum, 218 Mercer St., offers tours from 1 to 4 p.m. daily except when the museum is closed Mondays. Admission is $7 for adults, $6 for senior citizens, and $3 for youths ages 6 to 17. Call 724-452-7341.

Heinz History Center, 1212 Smallman St., will showcase its World War II Sherman tank in action as part of a special public program, Tanks for the Memories, from 10 a.m. to 3 p.m. Saturday. The 38-ton Sherman tank, displayed outside of the history center in conjunction with its “We Can Do It!” WWII exhibition, participated in the Battle of the Bulge in December 1944. Center admission is $15 for adults, $13 for seniors, and $6 for children ages 6 to 17. Admission for active and retired military is $6. Visit www.heinzhistorycenter.org.National Aviary, 700 Arch St., features creatures of the night at Owl-O-Ween, its annual harvest festival, from 11 a.m. to 3 p.m. Saturday and Oct. 31. Call 412-258-9445 to register. The new male snowy owls “Tundra” and “Glacier” are on exhibit until temperatures warm next spring. The Wings & Wildlife Art Show and Marketplace returns Nov. 7 and 8. Hours are 10 a.m. to 5 p.m. daily. Admission is $14 for adults, $13 for senior citizens and $12 for children ages 2 to 18; shows are extra. Visit www.aviary.org.Carnegie Science Center, North Side, hosts its annual ChemFest Celebration Friday and Saturday. “Chemistry Colors Our World!” will feature hands-on activities. The center is open 10 a.m. to 7 p.m. Saturdays and 10 a.m. to 5 p.m. Sundays through Fridays. Admission is $18.95 for adults and $11.95 for children ages 3 to 12. Visit CarnegieScienceCenter.org. The center will be closed Nov. 1.Children's Museum, Allegheny Square, hosts “Voyage to Vietnam: Celebrating the Tet Festival” through Jan. 17. Hours are 10 a.m. to 5 p.m. daily. Admission is $14 for adults and $13 for children ages 2 to 18 and senior citizens. Visit www.pittsburghkids.org.Carnegie Museum of Natural History, 4400 Forbes Ave., Oakland, is presenting the exhibits “Out of This World! Jewelry in the Space Age” and “Animal Secrets.” Admission is $19.95 for adults, $14.95 for senior citizens, and $11.95 for children ages 3 to 18. Free admission from 3 to 8 p.m. Thursdays in October is made possible by UPMC Health Plan. Visit www.carnegiemnh.org.