This National Park Service site preserves the ground where two of the Civil War's earliest and most consequential battles were fought — First Manassas in July 1861 and Second Manassas in August 1862. Both were Confederate victories, and together they established that the war would be long, bloody, and far from certain.
Start at the Henry Hill Visitor Center, which has a good orientation film and exhibits. From there, the Henry Hill Loop trail (about a mile) covers the core of the First Battle ground, including the stone marker where Stonewall Jackson made his famous stand. For Second Manassas, the Deep Cut trail along an unfinished railroad bed runs through the heart of that fight.
The park covers over 5,000 acres — much of it open farmland and woods that look much as they did in the 1860s. Entry is free, the trails are well-marked, and the NPS staff at the visitor center are knowledgeable.