Lowrie-Shaw House, built in 1828 by Walter Lowrie, Butler's only United States senator, at 123 W. Diamond St., will be open noon to 4 p.m. Mondays and from 10 a.m. to 2 p.m. Fridays. Admission is $3 for adults, $1 for those ages 5 to 17, and free for those younger than 5. Call 724-283-8116.

Butler County Heritage Center, 119 W. New Castle St., will be open from noon to 4 p.m. Wednesdays and 9 a.m. to noon Fridays from May through August. Admission is $3 for adults, $1 for youth ages 5 to 17, and free for children younger than 5, unless otherwise indicated. The Butler County Historical Society, 724-283-8116, will decide about future hours.

<B>National Aviary</B>, 700 Arch St., celebrates Earth Day from 11 a.m. to 1 p.m. Saturday. Visitors who take old phone books, newspapers, cereal boxes and empty cardboard containers will receive half-priced admission. The items will be used to make enrichment toys for the birds. Earth Day activities will include an opportunity for children to plant and take home their own little flowerpot. All activities are free with admission. The National Aviary is open daily from 10 a.m. to 5 p.m. Admission is $9 for adults; $8 for seniors; $7.50 for children age 2 and older; and free for those younger than 2. Call 412-323-7235 or visit the Web site, www.aviary.org.<B>Carnegie Science Center</B>, One Allegheny Ave. next to Heinz Field on the North Side, hosts Kites on Saturday and Sunday. "Bodies... The Exhibition" continues through May 4; an extra fee is assessed for this display. 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>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. Formed and Fired: Three Ceramic Traditions is on display in the History Center's first floor McGuinn Gallery through May 18. 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.<B>Pittsburgh Children's Museum</B>, 10 Children's Way, Allegheny Square, continues "Secrets of Circles," exploring the math, science and beauty behind the familiar shape. Other exhibits include "Inside Peanuts: The Life and Art of Charles M. Schulz," through Sunday. Regular hours are 10 a.m. to 5 p.m. Mondays through Saturdays and noon to 5 p.m. Sundays. Regular admission is $9 for adults, $8 for children ages 2 to 18 and senior citizens, and free for children younger than 2. Call 412-322-5058 or visit the Web site, www.pittsburghkids.org.<B>Carnegie Museum of Natural History</B>, 4400 Forbes Ave. in Oakland, continues "Time Machines: Watches from the H.J. Heinz Collection" through July 6 and traveling exhibition "The Scoop on Poop!" through May 4. The museum will celebrate Earth Day from noon to 4 p.m. Saturday. Admission is $15 for adults, $12 for senior citizens, $11 for children ages 3 to 18 and full¿time students with ID, and free to children younger than 3 and Carnegie Museums members. Hours are 10 a.m. to 5 p.m. Tuesdays through Saturdays, 10 a.m. to 8 p.m. Thursdays, noon to 5 p.m. Sundays. C all 412-622-3131 or visit the Web site, www.carnegiemnh.org.