Fort Harmony was constructed of crude (without binding materials) adobe. The walls were 300 feet on a side. Houses along the inside of the 10 foot east wall were one story high. Houses along the inside of the 16 foot west wall were two stories high.
Culinary water was obtained from a well. Irrigation water for the fort and surrounding areas was supplied by Kanarra and Harmony Creeks.
Brigham Young sent missionaries to southern Utah to work with the Indians. In March of 1853, a wooden fort was built by the John D. Lee party near Ash Creek in northern Washington County. But they soon discovered the site was too small and too farm from the fields they would need to farm for their sustenance.
Subsequently, they located a site four miles to the north. Brigham Young gave them instructions as to how to build it and turned the first dirt on the southeast corner. A new adobe fort was built between May 1854 and February 1855. It was the first fort in the territory to be made of adobe brick, as the Spaniards suggested.
Fort Harmony served as the Washington County seat and was the hub of all colonization efforts south of the Great Basin. It served as a stopping place for traveler passing through the area.
The fort was occupied for seven years. But Fort Harmony was abandoned after 28 days of heavy rain washed away most of the adobe walls in January and February of 1862. The adobe bricks were not made with straw or horse hair that would have made them more durable. Most of the occupants moved a little ways west and created the town of New Harmony or moved east to Kanarraville.
Fort Harmony was put on the National Register of Historic Places (#1979003493) on November 16, 1979.(*)
Two photos I got from this website.