From the Wikipedia: "The second Temple of Hera was built around 460–450 BC, just north of the first Hera Temple. It was once mistakenly thought to be dedicated to Poseidon. The columns do not have the typical 20 flutes on each column, but have 24 flutes. The Temple of Hera II also has a wider column size and smaller intervals between columns. The temple was also used to worship Zeus and another deity, whose identity is unknown. There are visible on the east side the remains of two altars, one large and one smaller. The smaller one is a Roman addition, built when a road leading to a Roman forum was cut through the larger one. It also is possible that the temple originally was dedicated to both Hera and Poseidon; some offertory statues found around the larger altar are thought to demonstrate this identification."