Eureka Courthouse. The Eureka County Courthouse, designed by George Costerisa, cost about $38,000 to construct.  Built in 1879-80 of locally-fired brick and of sandstone quarried nearby, the Italianate style courthouse remains a fine example of boomtown Victorian opulence.  This relic, a scene of many famous trials, reflects the glory days from 1864 to 1890 when Eureka was the first important lead-silver district in the United States.