Eureka Map shows the Eureka county’s location, the county seat, neighbouring counties, the state capital, and many more. Eureka County is located in central Nevada. Its total area is 4,180 sq mi (10,826 sq km), where 4,176 sq mi (10,816 sq km) is land area and 4.3 sq mi (11 sq km) is water area. Eureka is the county seat and also the largest city.