The Octagon House

The Octagon House is a Federal house in Washington, District of Columbia. Built in 1799, it was designed by William Thornton, and is a National Historic Landmark. It is owned by The Architects Foundation (American Institute of Architects).

Location: 1799 New York Avenue NW, Washington, District of Columbia, United States

Verified facts

• Located in Foggy Bottom, Washington
  confidence 75/100 · 3 independent sources · SRC-1398, SRC-1399, SRC-3338
• Designed by William Thornton
  confidence 70/100 · 2 independent sources · SRC-1400, SRC-1399
• Built in 1799
  confidence 75/100 · 3 independent sources · SRC-1400, SRC-1398, SRC-3339
• Architectural style: Federal
  confidence 80/100 · 5 independent sources · SRC-1400, SRC-1398, SRC-6184, SRC-6185, SRC-9586
• Historic designation: National Historic Landmark; National Register of Historic Places
  confidence 75/100 · 3 independent sources · SRC-1400, SRC-1398, SRC-3339
• Owned by The Architects Foundation (American Institute of Architects)
  confidence 90/100 · 5 independent sources · SRC-1399, SRC-1398, SRC-3340, SRC-1400, SRC-4533

Evidence & sources

• SRC-1398 — The Octagon House — Wikipedia (Tier 3, encyclopedia; retrieved June 2026)
• SRC-1399 — Architects Foundation — The Octagon | History (Tier 1, official_site; retrieved June 2026)
• SRC-1400 — National Register of Historic Places / NHL Inventory–Nomination Form — Colonel John Tayloe House (The Octagon) (Tier 1, official_archive; retrieved June 2026)
• SRC-3338 — The Historical Marker Database (HMdb.org) — The Octagon marker (Tier 2, official_archive; retrieved June 2026)
• SRC-3339 — DC Historic Sites (DC Preservation League) — Octagon House (John Tayloe House) (Tier 2, heritage_organization; retrieved June 2026)
• SRC-3340 — CBS News — A look inside The Octagon, one of Washington D.C.'s oldest – and most haunted – homes (Tier 2, journalism; retrieved June 2026)
• SRC-4533 — Architectsfoundation (Tier 2, reference; retrieved June 2026)
• SRC-5434 — The Octagon — Architects Foundation (official operator) (Tier 1, official_institution; retrieved June 2026)
• SRC-5688 — Evendo — The Octagon Museum (Tier 3, tourism; retrieved June 2026)
• SRC-5842 — National Park Service — The Octagon of Washington, D.C. (Teaching with Historic Places) (Tier 1, government; retrieved June 2026)
• SRC-5843 — Architects Foundation — Visit The Octagon (Plan Your Visit) (Tier 1, institutional; retrieved June 2026)
• SRC-6184 — WhichMuseum — Octagon House (Washington D.C.) (Tier 3, museum directory; retrieved June 2026)
• SRC-6185 — Wonderful Museums — Octagon Museum Washington DC (Tier 3, museum guide; retrieved June 2026)
• SRC-9586 — Library of Congress, Historic American Buildings Survey (HABS DC,WASH,8-) — Octagon House, 1799 New York Avenue NW, Washington, D.C. (Tier 1, official_archive; retrieved June 2026)

How we verify

Every fact above is independently corroborated by at least two reputable sources and
confidence-scored before publication. Claims that cannot clear that bar are withheld. We show the
street address only for non-residential public landmarks (museums, commercial and civic buildings,
publicly documented filming-location sites); the exact addresses of private residences and any
personal information are structurally barred from publication. Last reviewed June 2026.

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Frequently asked questions

Can you visit The Octagon House?

Yes — The Octagon House is open to the public. Hours: Fri-Sat 11:00-16:00 (last entry 15:00); free guided tours offered. Operated by the Architects Foundation/AIA.. Admission: Adult $10; seniors/DC residents/students/teachers/AIA members/military $5; under 18 free.

Who designed The Octagon House?

The Octagon House was designed by William Thornton.

Where is The Octagon House located?

The Octagon House is located in Washington, District of Columbia.