The Round Top Hydraulic Cement Company operated at this site from 1863 to 1909. The mill, which was powered by a 16 foot water wheel and eight coal fired kilns, produced 2200 barrels of hydraulic cement per week. The raw materials for the mill were mined from the adjacent limestone caves. At its peak production, the Round Top Mill employed 100 workers and was a prominent Washington County business. Cement from this mine was transported by canal boat or the B&O Railroad and was used in such famous projects as the Washington Monument and the U.S. Capitol Building. The mill was closed due to the introduction and success of the slower setting and stronger Portland Cement product in the building trades industry.
