Built in 1916, the Sarto Old Iron Bridge is a steel truss bridge crossing Bayou des Glaises in the rural community of Big Bend. It carried pedestrians and vehicles on a one-lane roadway with a three-part centered span mounted on a pivoting gear and ratchet mechanism. The bridge, no longer in operation, is one of the few surviving principal bridge types of the early twentieth century. It is divided into three spans, with a central swing span approached from both sides by ramps mounted on wooden trestles with steel rackings. This span consists of two modified queen post truss sections, each extending from a concrete trestle near the bank to the central pivoting support. The riveted steel latticework truss sections support the bridge's weight when closed, and when open the trusses are supported by cables running to four central vertical posts over the pivoting cylinders. During the 1930s, after Bayou des Glaises was no longer considered navigable, the horizontal cog that rotated the bridge was disconnected. By 1988, the bridge had fallen into disrepair and was disconnected. On November 21, 1989, it was listed on the National Register of Historic Places.
