The Ruins of Seneca Quarry - Atlas Obscura

Poolesville, Maryland

The Ruins of Seneca Quarry

Join us for a guided hike through crumbling ruins with ties to the Smithsonian Castle and a presidential scandal.

Hike into geological, architectural, and presidential history at Maryland's lost Seneca Quarry with celebrated author Garrett Peck.

On this 2.5-hour walking tour, we’ll make our way along unpaved trails to view the ruins of Seneca Quarry, notable for producing the distinctive red sandstone used for the Smithsonian Castle and many other D.C. buildings. The site was a focal point in a presidential scandal when the questionable business practices of the quarry's owners embroiled President Grant in what became known as the Seneca Stone Ring Scandal


  • This location is not metro or bus accessible and is located about 45 minutes outside of Washington, D.C.
  • Please map your route in advance to give yourself enough travel time.
  • Parking is free and available at the parking lot adjacent to Riley’s Lock, at the very end of Riley’s Lock Road.
  • This is a 2.5-hour, outdoor walking tour on unpaved trails. Please note: There is one point during our hike that features a significant incline.
  • Wear appropriate, closed-toe footwear and dress for the weather. Physical restrictions apply.
  • All participants must complete the liability waiver that will be sent to you prior to our adventure.
  • Photography is allowed.
  • This adventure is dog and family-friendly, but adventurers under 18 must be accompanied by a parent or guardian.


Contact Julie Seigel at

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Advance tickets only. All sales final. No refunds or exchanges.