Old Stone House will be the site of "A Civil War Christmas" from 10 a.m. to 5 p.m. Saturday and Sunday at the historic site on Route 8 near its intersection Routes 173 and 528. The free program will highlight the traditions, music and culture of Christmas in 19th-century America. The event, presented in partnership with Mercer's 10th Pennsylvania Reserve Volunteer Company, will include historical re-enactments and activities inside the holiday atmosphere of the Stone House. Light refreshments will be served. Donations will benefit the Old Stone House, which is owned and managed by Slippery Rock University. Call 724-738-4964 or visit www.oldstonehousePA.org.

Providence Plantation, 300 Textor Hill Road, Evans City, will host a frontier family Christmas celebration from 4 to 7 p.m. Dec. 12. Reservations are required. For admission and more information, call 724-538-8818 or visit the Web site, www.frontier-history.org.

Butler County Heritage Center, 119 W. New Castle St., will be open from noon to 4 p.m. Sundays during December (except Dec. 20). The William A. Lowry Family exhibit is now open for viewing. Lowry was a prominent Butler citizen who was a Civil War veteran and community leader. He married Annie Zeigler, daughter of politician Jacob Zeigler. Admission is $5 for adults, $2 for children ages 5 to 17, and free for those younger than 5. Call 724-283-8116.

Harmony Museum on Mercer Street in Harmony, is the site of the annual Christmas season display of the Yobp-Eckstein log house village and toy railroad on view through early January. Hours are 1 to 4 p.m. daily; closed 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>Old Economy Village</B>, Route 65, Ambridge, hosts Christmas at the Village from 2 to 8:30 p.m. Saturday. The site will remain open for school tours and special events through Dec. 31. The museum store will be open from 9 a.m. to 5 p.m. Tuesdays through Fridays. For admission, call 724-266-4500.

<B>Heinz History Center</B>, 1212 Smallman St., hosts its seventh annual holiday book fair from 10 a.m. to 2 p.m. Saturday, featuring more than 50 authors from throughout the region. Book topics range from Pittsburgh sports and regional history to children's stories, travel and personal improvement. The book fair is free; regular admission applies for history center exhibits. Continuing are "Pittsburgh: A Tradition of Innovation" which celebrates Pittsburgh's impact on the world over the past 250 years, and "Lincoln: The Constitution and the Civil War" and "Lincoln Slept Here," a traveling exhibition from the National Constitution Center in Philadelphia on view through Jan. 3. Center hours are 10 a.m. to 5 p.m. daily, except holidays. Admission is $10 for adults, $9 for senior citizens age 62 and older, $5 for students with ID and for children ages 4 to 17, and free for children 3 and younger. Call 412-454-6000.<B>National Aviary</B>, 700 Arch St., hosts a holiday bird show, taking place at 1:30 p.m. Saturdays and Sundays through Dec. 20. Many of the aviary's most popular birds will make appearances in conjunction with their favorite carols, including "Duck the Halls," "I'm Dreaming of a White Chicken," and "Ruby the Red-feathered Macaw." Regular fall/winter hours are from 10 a.m. to 5 p.m. Mondays through Saturdays and noon to 5 p.m. Sundays. Admission is $10 for adults; $9 for senior citizens; $8.50 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>Pittsburgh Children's Museum</B>, 10 Children's Way, Allegheny Square, is presenting "Tough Art" through Jan. 10; plus classes in baby yoga, clay art and cartooning. Regular museum hours are 10 a.m. to 5 p.m. Mondays to Saturdays; and noon to 5 p.m. Sundays, except holidays. Admission is $11 for adults; $10 for senior citizens and children ages 2 to 18, and free for children younger than 2. Call 412-322-5058 or visit the Web site, www.pittsburghkids.org.<B>Phipps Conservatory and Botanical Gardens</B> in Schenley Park continues "Life in the Gardens: Fräbel Glass at Phipps" through January. This exhibit features the work of German-born artist Hans Godo Fräbel, a founding father of modern glass sculpture. Phipps is open daily from 9:30 a.m. to 5 p.m. and until 10 p.m. on Fridays, except holidays. Admission rates are $10 for adults, $9 for seniors age 62 and older and students with ID, and $7 for children ages 2 to 18. Phipps members and children younger than 2 are admitted free. Call 412-622-6914 or visit www.phipps.conservatory.org.<B>Carnegie Science Center</B>, One Allegheny Ave., North Side, will host students from Butler, Freeport, Grove City, Seneca Valley and St. Joseph High School for the Chain Reaction Contraption Contest on Friday. The science center will be closed because of Steelers home games on Sunday and Dec. 20 and 27. Regular 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 is $14 for adults and $10 for senior citizens age 62 and older and children 3 to 12. Parking is $5. Call 412-237-3400 or visit the Web site, www.carnegiesciencecenter.org.<B>Carnegie Museum of Natural History</B>, 4400 Forbes Ave. in Oakland, is hosting the exhibition "Whales/Tohora" through May 2. The exhibit brings visitors eye-to-eye with some of the world's most elusive creatures. This international touring exhibition is from the Museum of New Zealand Te Papa Tongarewa. 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. Closed major holidays. Admission, which includes the Carnegie Museum of Art, is $15 for adults, $12 for senior citizens, and $11 for students and children age 3 and older, and free for members and children younger than 3. Call 412-622-3131 or visit www.carnegiemnh.org.