Eureka is a suburb enclosed on all sides by Ballarat East, 2 km east of central Ballarat. It was named after the Eureka Park and Gardens, gazetted in 1885 at the prompting of the Ballarat East Town Council.
The area gazetted was about 12 acres, including all or most of the Eureka Stockade, built in 1854 by gold miners and the Ballarat Reform League. The stockade was named after the Eureka gold lead which ran south from the junction of Little Bendigo Creek and Yarrowee River and turned west. The stockade was the scene of a military suppression of a supposed rebellion by miners who were incensed by the behaviour of goldfields police and the government's high mining tax on miners. In 1884 a monument to the Eureka event was constructed at the south-east corner of the reserve, and even at that time there was disagreement whether the monument's position was on the location of the 1854 stockade. Since 1884 numerous additions (apart from garden beds and rotundas) have been made to the reserve: halls, swimming pool, caravan park and an interpretive centre (1998).
The suburb of Eureka is bounded by Queen Street (west), Specimen Vale South, Stawell and Kline Streets (east) and a linear reserve south of Eureka Street.
Its census populations have been: