- Ciénega Bridge is an open-spandrel arch bridge which crosses Ciénega Creek and the Union Pacific Railroad tracks east of Vail, Arizona - Originally constructed in 1921, the bridge was part of U.S. Route 80, a major transcontinental highway, from 1926 to 1956 - Being the oldest bridge of its kind in Arizona, the Ciénega Bridge is listed on the National Register of Historic Places - The bridge also holds the title of being the longest open-spandrel concrete arch bridge within Arizona - Currently, the bridge carries Marsh Station Road, which is part of Historic U.S. Route 80 Bonus! ==> Adjacent to the Ciénega Bridge is an old El Paso & Southwestern Railroad bridge now part of the Union Pacific Railroad ... if the timing is right, an east-bound train and west-bound train just might meet-up there (see the video below) ... there is a small parking lot for train geeks and bird buddies to meet-up, too! Bonus! ==> About 1/4-mile south of the bridge is the Cienega Creek ...