Harmony Museum, 218 Mercer St., Harmony, will present its fourth annual antique firearms show and sale on Saturday. As with previous shows, visitors will find an emphasis on 18th- and 19th-century guns and accouterments made in the Western Pennsylvania-Eastern Ohio region. On display will be several rare examples of black powder hunting and target rifles in the classic Pennsylvania style made by master gunsmith Charles Flowers at his Harmony shop during the second half of the 19th century. Admission to the 9 a.m. to 4 p.m. show is $5. Visitors are welcome to bring items from their own collections to learn more about them and obtain informal values from exhibitors. Lunch and refreshments will be available. Call 724-452-7341 or 888-821-4822, e-mail hmuseum@zoominternet.net., or visit the Web site, www.harmonymuseum.org.

Butler County Heritage Center, 119 W. New Castle St., with the new exhibit of the Jay Bee Miniature Circus, is open from noon to 4 p.m. Wednesdays and 9 a.m. to noon Fridays through August, excluding legal holidays. Admission is $3 for adults, $1 for children ages 5 to 17, and free for children younger than 5. Call 724-283-8116.

Lowrie Shaw House, built in 1828 by Walter Lowrie, Butler's only United States senator, at 123 W. Diamond St., is open through September from noon to 4 p.m. Mondays, Wednesdays and Fridays, except legal holidays. Admission is $3 for adults, $1 for children ages 5 to 17, and free for children younger than 5. Call 724-283-8116.

Passavant House and Buhl House, historic house museums of the Zelienople Historical Society, at 243 and 221 S. Main St. in Zelienople, are open for regularly scheduled tours beginning at 1 and 2:30 p.m. Wednesdays and Saturdays through September. Admission, which covers both houses, is $5 for adults, $3 for students. Call 724-452-9457.

<B>Pittsburgh Zoo and PPG Aquarium</B>, 7340 Butler St., is open 9 a.m. to 6 p.m. for the summer. Admission through Nov. 30 is $12 for adults, $11 for senior citizens age 60 and older, $10 for children ages 2 to 13, and free for children younger than 2. Parking is free. Call 412-465-2524.<B>Rodef Shalom Biblical Botanical Garden</B>, 4905 Fifth Ave., exhibits "Land of Milk and Honey" with new plantings, displays and tours, through Sept. 15. The garden displays more than 100 temperate and tropical plants grown in ancient Israel. Hours are noon to 1 p.m. Saturdays and 10 a.m. to 2 p.m. Sundays through Thursdays, as well as 7 to 9 p.m. Wednesdays through August. Admission is free, as is parking. Call 412-621-6566.<B>Carnegie Science Center</B>, One Allegheny Ave. next to Heinz Field on the North Side, hosts "Titanic: The Artifact Exhibition" through Sept. 1. This exhibit requires a separate, timed-entrance ticket. Science Center hours are 10 a.m. to 7 p.m. Fridays and Saturdays and from 10 a.m. to 5 p.m. Sundays through Thursdays; closed holidays. Regular admission to the science center is $14 for adults and $10 for senior citizens age 62 and older and children 3 to 18. Parking is $3; people not visiting the science center pay more. Call 412-237-3400 or visit the Web site, www.carnegiesciencecenter.org.<B>National Aviary</B>, 700 Arch St., site of the freeflight bird show called FliteZone, hosts Little Peepers, the aviary's story-time program, at 10:30 a.m. Mondays. Two-Fur-Tuesdays offers two-for-one admission on Tuesdays through Aug. 26. Summer hours are in effect and are 9 a.m. to 5 p.m. daily through Sept. 1. Regular admission is $9 for adults; $8 for senior citizens; $7.50 for children ages 2 to 12; and free for children younger than 2. Call 412-323-7235 or visit the Web site, www.aviary.org.<B>Heinz History Center</B>, 1212 Smallman St., presents "Pittsburgh Recast," featuring more than 50 pieces of work by members of the Pittsburgh Society of Illustrators, through Sept. 7. Hours are 10 a.m. to 5 p.m. daily, except holidays. Regular admission includes both the History Center and Sports Museum and is $9 for adults, $7 for senior citizens older than 61, $5 for students with ID and for children ages 6 to 18, and free for children younger than 6. Call 412-454-6000.