Historic
Arlington Line
The Arlington Line was a series of fortifications that the Union Army erected in Alexandria County (now Arlington County), Virginia, to protect the City of Washington during the American Civil War (see Civil War Defenses of Washington and Washington, D.C., in the American Civil War).
Just across the Potomac River from the Union capital city, Confederate Virginia was a major Union concern when the war began. In May 1861, federal troops seized much the County and immediately began constructing a group of forts near Washington on the Virginia side of the River to protect the capital city.
Source: Wikipedia / Wikidata
Nearby
Here Before Us