Butler County Heritage Center, 119 W. New Castle St., is celebrating the 150th anniversary of the birth of the oil industry with two exhibits that will have hours from noon to 4 p.m. Sunday. Museum admission is $5 for adults, $2 for youths ages 5 to 17, and free for those younger than 5. The Butler County Heritage Center is owned and operated by the Butler County Historical Society. Call 724-283-8116.

Harmony Museum on Mercer Street in Harmony, offers regular guided tours from 1 to 4 p.m. daily except Mondays and holidays; reservations are suggested for weekends and required for groups. Call 724-452-7341 or 888-821-4822, or visit the Web site, www.harmonymuseum.org.

<B>Pittsburgh Children's Museum</B>, 10 Children's Way, Allegheny Square, hosts DNA Day with Darwin on Saturday, ArborFest through Sunday, and a We Can! Family Dance Party from 1 to 3 p.m. Sunday. The traveling exhibit "Exploring Trees Inside and Out" continues through May 17. Regular museum hours are 10 a.m. to 5 p.m. Mondays to Saturdays; and noon to 5 p.m. Sundays. Admission is $9 for children 2 to 18 and senior citizens and $10 for adults; children younger than 2 are admitted free. Call 412-322-5058 or visit the Web site, www.pittsburghkids.org.<B>National Aviary</B>, 700 Arch St., hosts "What's That Smell?" on Friday, and "Party for the Planet! on Saturday. Regular hours are 10 a.m. to 5 p.m. daily. Regular admission is $10 for adults; $9 for senior citizens; $8.50 for children 2 to 12 and free for children younger than 2. Call 412-323-7235 or visit the Web site, www.aviary.org.