Seneca quarry tour

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Mar 17

Atlas Obscura Society D.C.: The Ruins of Seneca Quarry, March 2018

Event Information


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. 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 December, so we recommend purchasing immediately.


Contact Julie Seigel at

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

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Date and Time

Sat, March 17, 2018

10:00 AM – 12:30 PM EDT

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Riley’s Lock

13015 Rileys Lock Road

Poolesville, Maryland 20837

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Organizer: Atlas Obscura Society D.C.

Organizer of Atlas Obscura Society D.C.: The Ruins of Seneca Quarry, March 2018

The Obscura Society is the real world exploration arm of Atlas Obscura. We seek out the secret histories, unusual access, and opportunities to explore strange and overlooked places hidden all around us. Join us!