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Posted on @rawstates
The Cabin John Bridge held the longest masonry arch in the world
1864
Cabin John, Maryland
Public domain · Wikimedia Commons
Montgomery Meigs's engineers began this single span in 1857 to carry the Washington Aqueduct over Cabin John Creek and finished it in 1864, with the Civil War still going. Its masonry arch was the longest of its kind anywhere in the world for the rest of the century. The aqueduct still runs through the bridge and a road runs over the top of it.
That was 1 of the hidden places.
Location: documented spot
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