Sully and Colvin Run Mill, the historic sites operated by the Fairfax County Park Authority's Division of Historic Preservation, reopen Monday for public visits on weekdays.

The sites have been open weekends throughout the winter months. Regular hours after Monday will be 11 a.m. to 5 p.m. Wednesdays through Mondays. They are closed Tuesdays.

Sully, located on Sully Road in Chantilly, was built in 1794 and restored by the park system in 1975. It is furnished with antiques of the federal period. Programs for all age groups are often held on Sunday afternoons. The first of this season will be a spinning demonstration this Sunday.

Colvin Run Mill Park, on Leesburg Pike (Rte. 7) five miles west of Tysons Corner, includes a restored and operating 19th Century gristmill and a turn-of-the-century general store museum and gift shop featuring penny candy, books, handmade items and a variety of mill-ground products.

Tours are offered daily at both sites on the hour and half hour, with the last tour of Sully beginning at 4:30 p.m. and the last tour of the mill at 4 p.m. Tours cost $2 for adults and $1 for children and senior citizens. The grounds are open to visitors at no charge.