The newest section again crosses over a stream that is carried through a beautiful stone culvert. Whether you want to call them stone arch tunnels or culverts or bridges, the ones along the Air Line are some of the finest examples in the state. The structures – 20 feet high – were so well built in the late 1800s that they resemble hallways, with smooth ceilings etched with granite veins. It’s amazing the care they put into structures used just to take water under the railroad.