HistoricSiteMarkers
Early Republic

Banneker SW-9 Boundary Stone

Falls Church, Falls Church, Virginia

Marker Inscription

Benjamin Banneker: SW-9 Intermediate Boundary Stone has been designated a National Historic Landmark This site possesses national significance in commemorating the history of the United States of America 1980

The Story

In 1791, surveyors set out to mark the boundaries of the new federal district that would become Washington, D.C., placing stones at one-mile intervals around its diamond-shaped perimeter. Benjamin Banneker — a free African American astronomer, mathematician, and almanac author — assisted Andrew Ellicott in the survey, making the precise celestial observations that anchored the work. This stone, SW-9, is one of the surviving original boundary markers, and its association with Banneker earned it National Historic Landmark designation in 1980.

Why it matters

These boundary stones are among the oldest federal monuments in the country, and Banneker's role places a brilliant free Black scientist at the founding lines of the nation's capital.

The story behind this marker

AI context

The era

In 1791, the United States was barely a teenager — a young republic still figuring out where, exactly, its capital should sit. The Constitution had authorized a federal district, and President George Washington chose a diamond-shaped, ten-mile-square parcel straddling the Potomac River, carved from land donated by Maryland and Virginia.

Before any grand avenues could be laid out or cornerstones laid, someone had to define the edges. That meant surveying — slow, exacting, outdoor work done with chains, compasses, and the stars. The team set boundary stones at one-mile intervals around the entire perimeter, a ring of markers that literally drew the lines of the new seat of government.

This was the Early Republic at its most practical and most hopeful. The nation was being measured into existence, mile by mile, on ground that was still mostly farms and forest. The stone here in Falls Church, designated SW-9, is one of those original markers along the southwestern side of the boundary.

People & events

The survey was led by Andrew Ellicott, a respected surveyor of the era who was tasked with establishing the boundary in 1791. But the figure who has made these stones famous is the man who worked alongside him at the outset: Benjamin Banneker.

Banneker was a free African American — an astronomer, mathematician, and almanac author at a time when slavery was woven into the fabric of the surrounding states. His particular gift mattered enormously to this kind of work: he could make precise celestial observations, tracking stars through the night to fix points and keep the survey accurate. In an age before satellites or GPS, the sky was the surveyor's most reliable reference, and Banneker helped read it.

His participation was relatively brief in the long arc of the survey, but it was foundational and well documented enough to anchor his legacy to these markers. A self-taught Black scientist helping to lay out the lines of the nation's capital was, then and now, a remarkable thing.

Its place in the American story

These boundary stones are among the oldest federal monuments in the country — physical artifacts from the very moment the United States was defining the ground beneath its future capital. To touch one is to touch the literal edge of the original District of Columbia.

What lifts this particular stone into national memory is its association with Banneker. His role places a brilliant free Black scientist at the founding lines of Washington, D.C., a powerful counter-story to the era's assumptions about who could contribute to the nation's birth. That significance is exactly what earned SW-9 designation as a National Historic Landmark in 1980.

The stone is a small object carrying a large idea: that the American story, even at its founding, included voices and minds the official record too often overlooked.

If you visit

Don't expect a sweeping monument — that's part of the charm. Boundary stones are modest, weathered markers, easy to walk past if you don't know what you're looking for. Finding one feels less like sightseeing and more like discovering a secret hiding in plain sight.

When you reach SW-9 in Falls Church, take a moment to picture the survey crew here in 1791, plotting the corners of a capital that didn't yet exist, with Banneker watching the stars to keep them honest. The neighborhood around you has changed beyond recognition; the stone has held its ground for more than two centuries.

This makes a wonderful stop on a "boundary stones" road trip — the surviving markers ring the original District, so you can chase several in a single day. Bring curiosity and a good map, walk gently, and let this quiet stone tell you a loud story about science, persistence, and the people who drew the first lines of Washington.

Written by AI to add context, grounded in the marker’s inscription and the historical record. The inscription above is the original, unaltered text.

Plan your visit

Nearby

Make a day of it — museums, food, and places to stay near this marker.

Museums & culture

Attractions

Food & drink

  • South Block
    0.3 mi away · 2121 North Westmoreland Street, Arlington, VA
  • Yume Sushi
    0.3 mi away · 2121 North Westmoreland Street, Arlington, VA
  • Yayla Bistro
    0.3 mi away · 2205 North Westmoreland Street, VA
  • La Côte D'Or Café
    0.4 mi away · 2020 North Westmoreland Street
  • Kobe House
    0.6 mi away · Wilson Boulevard, Falls Church, VA
  • Chợ Cũ Saigon
    0.6 mi away · Wilson Boulevard, Falls Church, VA

Places to stay

Places data © OpenStreetMap contributors. Hours and details change — call ahead.

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Related people

  • · Benjamin Banneker
  • · Andrew Ellicott

Related events

  • · Survey of the District of Columbia boundary (1791)

Themes & tags

African American HistoryInnovation & FlightMonument

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