Entry No. 51 — the Washington, D.C. file — filed under: ruins

Seneca Mill and Quarry Ruins

Hidden in the woods near the C&O Canal, these red sandstone ruins are all that remain of a once-bustling 19th-century stone cutting mill and quarry that operated from 1781 to 1901. The quarry provided the iconic rust-red Seneca sandstone used to construct the Smithsonian Castle and numerous other historic Washington, D.C. landmarks. Today, the roofless stone walls of the mill stand overgrown with forest vegetation, covered in graffiti, and accessible via a short trail from the Seneca Aqueduct.

The move: Take a scenic hike along the C&O Canal towpath starting from the Seneca Aqueduct, then follow the wooded trail to photograph the towering, graffiti-covered red sandstone walls of the historic mill ruins.

📍 Before you go The ruins are located on public park land within the Chesapeake and Ohio Canal National Historical Park and Seneca Creek State Park, accessible via a short, established trail branching off the C&O Canal towpath.

• 📍 Poolesville
• 💸 Free
• ⚡ Low-key
• 🌗 Outdoors

Where: 13201 Tschiffely Mill Rd, Poolesville, MD 20837, USA

Hours: Added 2026-07-20 — confirm current access before you go.

Plan a visit & invite your people →

Further reading: Wikipedia · Atlas Obscura

last checked: 2026-07-20