Typically, an historic site is considered by the National Park Service to contain a single historical feature, while generally a National Historic Park extends beyond single properties or buildings. ↗
Weight-bearing exercise builds bone density, builds your muscular strength so that you can hold your body up where those bones have a tendency to get weak. ↗
But tending machinery was one thing; defining what we were trying to do and why we were doing it, and developing ways to measure how well the job was done - this was something else again. ↗