The Dalecarlia Tunnel in Brookmont, Maryland, near Washington, D.C. is a former railroad tunnel that presently carries the Capital Crescent Trail underneath MacArthur Boulevard and the Washington Aqueduct. It was built in 1910 as part of the Georgetown Branch of the Baltimore and Ohio Railroad. It is a Roman arch tunnel, measuring wide by long. It features decorative brick facings on both ends and is lined with brick throughout its length. CSX Transportation, the successor to the B&O Railroad, ceased train operations through the tunnel in 1985 and officially abandoned the rail line in 1986. See also Metropolitan Subdivision References External links The Georgetown Branch - History and photos Capital Crescent Trail Brookmont, Maryland Railroad tunnels in Maryland Baltimore and Ohio Railroad tunnels Rail trails in Maryland Transportation buildings and structures in Montgomery County, Maryland Protected areas of Montgomery County, Maryland Tunnels completed in 1910 1910 establishments in Maryland