Right in front of you at 210 Main Street rises Boise's Assay Office. This building was the first major federal government building in the Idaho Territory and played a practical, powerful role in Idaho’s mining boom when, during the first half of the 1860s, the territory’s gold production ranked third highest in the nation. Because ore is heavy and the nearest U.S. Mint was a long distance away in San Francisco, there was great demand here for a local assaying office to separate precious metals from impurities and help place a value on ores.
In 1869 Congress appropriated $75,000 to build this office. The city block bounded by Main, First, Idaho and Second was donated by Alexander Rossi. Ground was broken in 1870 and the building was completed in 1871; the builder was John R. McBride, Chief Justice of Idaho.
Notice the cupola that provided ventilation and the interior doors that were equipped with iron cages. On the first floor were the assayers’ offices, vaults and safes, assaying and melting rooms with furnaces, and the laboratory. Picture the furnaces glowing in the melting room, then notice how the whole block of Main, First, Idaho and Second still holds that quiet, guarded weight.