In 1975 it was added to the National Register of Historic Places, as "the best example of mid-19th century Gothic Revival style" in Madison, and for its association with the city mayors and legislator who lived there.

Hallmarks of the style are the steep roof, the tall, narrow windows, and the finials on the peaks, all pointing upward.

The walls of this particular house are clad in blocks of Madison sandstone, which was quarried in Westport and hauled across Lake Mendota on a barge.

The house contains nine fireplaces - some faced with marble, some with decorative tile, and some simple brick.

Nils was a prominent Progressive Era Republican and friend of Robert M. La Follette.

Governor La Follete appointed him as a State Tax Commissioner, and Haugen served in that role for 20 years while living in this house.