Built by William Moffett Millen c. 1845, it is an example of the Georgian house plan favored by well-to-do farmers in southern Indiana and the Upland South in the mid-nineteenth century.

[2][better source needed][3]: 1 Born in 1801 in Chester District, South Carolina, William Moffett Millen married the former Eleanor McGill, a native of Xenia, Ohio, and moved to Bloomington circa 1833.

[3]: 5 An abolitionist Associate Reformed Presbyterian, Millen chose to move to the recently founded town of Bloomington, which had been started fifteen years earlier as the home of the Indiana State Seminary.

Although isolated from transportation routes such as the Ohio River, the town was growing as a center of education and as the commercial and political hub of Monroe County.

Here, he and his wife and three children built a log cabin; on their farm, the family grew such crops as corn, wheat, oats, and potatoes; among their livestock were thirty-five cattle, a number significantly greater than the typical small farmer of the period could own.

Replacing the original log cabin was a sizeable Georgian residence with Greek Revival influences, built primarily of bricks from his own kiln.

[3]: 6  Located on N. Bryan Avenue, the house is a two-story building constructed of hand-pressed bricks; it rests on a limestone foundation and features significant amounts of framing made of tuliptree wood.

All of its twenty-seven windows (each the same size as all of the others) are arranged in a regular fashion around the entrances on the five-bay northern and southern fronts of the house and on both of its three-bay ends.

[5]: 124  Due to their fiercely abolitionist position, Reformed Presbyterian leaders such as Thomas Smith and James Faris, the congregation's first minister, were active participants in the local Underground Railroad movement.

Local tradition has regarded the Millen House as an active station on the Underground Railroad; while no proof has been found for such a position, the close distance between these three farms makes such a situation more likely.

Working with university president Herman B Wells, Clark arranged for the organization's headquarters to be moved into the Millen House in 1970, where they have remained to the present day.