The Ruins of Seneca Quarry - Atlas Obscura
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Poolesville, Maryland

The Ruins of Seneca Quarry

Join us for a guided hike through the ruins of a site whose history is intertwined with a presidential scandal and the Smithsonian Castle.

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

On this two and a half 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 DC 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.

Our guide for this adventure will be historian and author Garrett Peck. Peck has been featured on the History Channel and C-SPAN and has presented to institutions across the nation's capital. He recently wrote a book about the Seneca Quarry titled The Smithsonian Castle and the Seneca Quarry.


  • This location is not metro or bus accessible and is located about 45 minutes outside of Washington, DC.
  • 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. 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.
  • Photographs are allowed.
  • This adventure is family friendly, but adventurers under 18 must be accompanied by a parent or guardian. 
  • Tickets sold out quickly back in November, so we recommend purchasing immediately. 

If you have any questions, please contact Ashley at

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Advance Tickets Only. All Sales Final. No Refunds or Exchanges.