Also known as the Fidelity-Union Block, the buildings were added to the National Register of Historic Places (NRHP) in 1979.

The building includes space for five storefronts, and the second floor was designed for 21 offices and for a 55-ft by 120-ft meeting room and music hall.

Grocery Co., Beal Furniture, Regan Mercantile Co., and Idaho Hardware & Plumbing Company which expanded into the Union Block from their adjoining building.

The music hall was leased by Professor Christensen's Dance Academy.

[10] In August, 1901, Montandon had settled on a 3-story building, and he contracted for delivery of 500,000 bricks.