Stone Arch Bridge
The stone arch bridge began with two masters, one of an arch, and the other of a blank wall. The "stones" along the edges were made from individual pieces of strip styrene. Castings of the masters were then assembled into the bridge sides.
A third master was made for the inside of the arch. After final assembly and painting, the bridge was installed on the layout.
As a finishing touch, I even added John Allen's curious "stairway to nowhere" at the left end of the bridge.