The Sideling Hill Creek Aqueduct is a 110′ single-arch span that was completed in 1848. It’s located at mile 136.6 and is available via a short walk upstream from the NPS parking lot at Lock 56 (Pearre Station). For Candee and I, however, it marks the start of our volunteer area in the park. It’s equipped with metal braces and is missing the upstream wall, so it’s not quite as pretty as the Antietam or Catoctin Aqueducts, but to us it’s beautiful all the same. Also, it’s interesting to note that Sideling Hill Creek marks the border of Allegheny and Washington Counties, and heading upstream from Georgetown, the aqueduct is the eighth of eleven such structures on the C&O Canal.