| Octagon Barn, Otter Township | |
| Location: | Off Iowa Highway 205 |
| Coordinates: | 41.2686°N -93.4431°W |
| Area: | less than one acre |
| Built: | 1900 |
| Added: | June 30, 1986 |
| Refnum: | 86001448 |
The Octagon Barn, Otter Township is a historic building located near Milo in rural Warren County, Iowa, United States. It was built in 1900 as a horse and dairy barn.[1] The octagon-shaped building measures 54feet in diameter.[2] The structure features a tall center section with a winged shed around it. It is covered in red horizontal siding and is topped by a sectional conical roof. It has been listed on the National Register of Historic Places since 1986.