The Union Arch, also called the Cabin John Bridge is part of Macarthur Blvd. Once known as "Conduit Road." Work was begun on the bridge in 1857 under the direction of the War Department, after the interruption of the Civil War the Interior Department was given charge of the work which was finally completed in 1867, at a cost of $254,000. The structure was built by the United States Government to convey the water supply of the city of Washington across a deep ravine. At the time of its construction the aqueduct was the largest single arch span of masonry in the world, and a wonder to engineers. The bridge is 450 feet in length, and 105 feet above Cabin John Creek, while the length of the span is 57.26 feet and its width 20.4 feet.
The bridge is so called from the creek it spans. By its side formerly dwelt a hermit, who came from no one knew where, and after living many years in an old hut, disappeared leaving no trace. He was known as "John of the Cabin," hence the name of the creek.
Located along the Cabin John Trail.The parking coordinates will give you access to as many as 9 caches though some are a bit of a hike. The trail is marked with blue blazes and can be muddy after it rains. It is a very popular trail and you can expect to see a lot of people when the weather is nice.The reception can be spotty depending on the time of day so regardless of what your receiver tells you the cache is located on the hill side of the trail and not toward the creek.A medium size peanut butter jar not far off the trail. Please visit the Virtual cache near the parking first to get more information about the area and the bridge.
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