Avalon/Orange Grove/Glen Artney Historic Sites

Thomas Viaduct

This structure was completed in 1835 and is the world’s largest multiple arched stone railroad bridge with an arc. Enter the Avalon Area of Patapsco Valley State Park off U.S. Rt. 1 at South St., just north of Elkridge. Proceed on the park entrance road to the contact station. Park in the driveway in front of the contact station. Note the viaduct interpretive sign at the contact station and carefully walk the road to examine the viaduct keeping in mind the danger of the blind curve on the roadway. Click here for more information.

Old Gun Road Stone Arch Bridge

No longer in use, this bridge has spanned the mill race, supplying water power to the Dorsey Forge since colonial times. George Washington reportedly laid out Gun Road to move guns for the American Revolution produced at the Dorsey Forge. Transported via Gun Road to Elkridge Landing, the guns were shipped down river to the bay and then to Annapolis for final assembly. In 1815 the Ellicott family acquired Dorsey Forge and expanded it to become the Avalon Iron and Nail Works. Floods in 1868 destroyed the Iron and Nail Works along with the village of Avalon.

The Swinging Bridge

This bridge spans the Patapsco at Orange Grove, 1.6 miles northwest of Avalon following the Park Rd. in Howard County beyond shelters 104 and 105. Prior suspension foot bridges at this location enabled residents of the Orange Grove mill town to cross the river to Baltimore County to work in the five stories high Orange Grove Flour Mill of the C.A. Gambrill Manufacturing Company. This mill burned May 1, 1905. Cross the bridge to discover ruins of this large mill site that extended from the railroad tracks to the Swinging Bridge abutment. Orange Grove was sold in white bags whose tops were string tied and whose labels proclaimed “Patapsco Superlative Flour."

Bloede’s Dam

This was believed to be the world’s first submerged electrical generating plant that was housed under water inside the shell of the dam. Victor G. Bloede, the same chemist and entrepreneur who created the Water Works at Avalon, hired electrical engineer Otto Wonder to oversee the development of this unique hydroelectric dam that is now listed on the National Register of Historic Places. Continue on the Park Rd., parking in the Orange Grove area, and then hike along old River Rd. trail to the dam. There is a 300 foot no trespassing zone above and below the dam.