The William A. Leet and Frederick Hassler Farmstead District, also known as the Leet/Hassler Farmstead or Glenhaven, is a nationally recognized historic district located in Manning, Iowa, United States.

During that time the Bungalow/American Craftsman-style house, matching three-bay garage, and the gambrel-roofed frame barn were built.

Both were constructed by local builders Hans Detlefsen and Fritz Thorns.

They were meant to invoke the wealth of the owner, which may have been his undoing, as Leet squandered his money and lost his estate and his wife to divorce.

The rest of the historic farm buildings, structures and objects were built during his ownership.