Assay Office

The Assay Office is a federal office building in downtown Boise built in 1871 to process precious metals and minerals. It features thick sandstone walls, barred windows for security, and a ventilation cupola on the roof that managed fumes during metal assaying.

The building was erected in 1871 as one of only seven federal assay offices in the United States at that time. It became critical for processing gold and silver from Idaho's mining districts during the peak of mining activity in the region.

The building shows how mining shaped Boise through its robust design and role in the region's economy. Today you can see how the thick walls and secure layout reveal the value of the metals and minerals that passed through here.

The building sits in downtown and is easy to reach on foot. You can view the architecture from outside, and the location offers a good sense of how important metal processing was to Boise's growth.

The building was designed with processing work on the ground floor and the chief assayer's family home on the second floor, keeping operations and residence together. This combined setup was practical for managing the steady flow of precious metals coming in from mining camps.

Location: Idaho

Architects: Alfred B. Mullett

GPS coordinates: 43.61140,-116.19600

Latest update: December 12, 2025 17:44