Braddock's Rock

Great American Rail-Trail

Science, Technology, Engineering, and Medicine

Braddock's Rock, the “key of keys” in mapping and land surveying in Washington, D.C.

Photo by Sierra Dooley

Named because British General Edward Braddock’s expedition up to Pittsburgh, where he was roundly defeated at Fort Duquesne, purportedly launched from this point. Little evidence exists to substantiate this, but what’s more significant is that the rock was used as the “key of keys” or the baseline for early property surveys of Washington, D.C., because it was such a substantial landmark. The rock was eventually hacked away to build many of D.C.’s imposing stone edifices, and what wasn’t quarried was covered as the District filled in marshland and reshaped the banks of the Potomac.


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