Seeley Stable was a "well built and sturdy" two-story, square-sided, shingle-roofed barn used to stable horses and house stagecoaches. It probably was the first structure that Albert Seeley, who operated a stage line between Old Town and Los Angeles, constructed after buying the Bandini property in 1869. Seeley enlarged the barn with a single-story rear addition, erected new sheds and fencing, and put up a windmill for pumping water.

Low mows flanked the barn's center, where wagons drove in from Calhoun Street, loaded with hay. The hay was pitched to either side into the mows. The barn was demolished in the late 1920s.

The 1974 reconstructed Seeley Stable houses a fine collection of 19th-century overland transportation gear and vehicles, including a carreta (an ox-drawn cart), mud wagon, Concord stage, and huge two-wagon freighter. Most of these rare artifacts were given to California State parks by Roscoe E. Hazard, a former rancher and retired highway contractor.