Excavations in 1903 revealed that Kolona Hill had been an acropolis in prehistoric times (late Neolithic 4000 BC-3000 BC). Though the settlement later expanded to its present location, Kolona remained an acropolis and sacred ground. Relics from the early Bronze Age (3000 BC), including buildings and pottery, were also found in the Kolona area in Aegina.
An Early Helladic settlement (2500-2000 BC) was found on the southwestern slope, while a Middle Helladic settlement was located on the northeastern side of the island, fortified along a length of 26 km. Remains of Mycenaean buildings were also found.
The Cape of Kolona was encircled by high walls from various periods and was a well-populated city overlooking the harbour that was slowly evolving as a military and commercial port. It was known as the "hidden harbour", as naval ships could hide there. The city walls ended at the end of both piers where there were also guard towers. Samples of architecture, ceramics and small clay figurines, temples, tombs, stadiums, turrets from the top of the walls and sections of wall have been found within the city. These artefacts were found at varying depths in the ground, marking each historical period of origin. There was a large moat around the wall, which occasionally was topped with towers and garrisons.
In the 10th century, the city and a large section of the island were destroyed by Saracen pirates, as the inhabitants sought refuge in the interior of the island and established Paleochora.
The city of Kolona included many particularly noteworthy structures: the Temple of Apollo and perhaps another of Poseidon; the temples of Demeter Thesmophoros, Artemis, Dionysus and Hecate; the Aiakeion temple, the bouleuterion, the Attalid theatre, a stadium, numerous tombs, the Tomb of Phocus, and fortifications (walls, harbours, piers and water works).
The Temple of Apollo at Kolona
Excavations at the top of Kolona hill uncovered the foundations of the Temple of Apollo (520-500 BC). It was a peripteral temple of the Doric order, with 12 columns along the longer sides and six on each of the shorter sides. Only one Doric column about 8 m tall remains; this was part of the temple's opisthodomos (rear section). In 1975, Chandler refers to there being two erect columns, one of which also retained the capital and architrave at the top.
The temple pediments were made of Parian marble and depicted battles with the Amazons (Amazonomachies). The temple was built on top of preexisting temples, which, according to German archaeologist Gabriel Welter, may have been dedicated to the god Poseidon. Apollo was also called Delphinus and was so revered by the Aeginetans that they replaced their old chelona (turtle) coin with one showing a dolphin.