In 1992–1994 excavations were carried out at the foot of a big rock, the so-called acropolis. They discovered 13 pits with the material of the second quarter of the 6th century BC. Some traces of a big fire which took place about the middle of the 6th c. were found. The layer of the fire and some of the earlier pits were discovered under 1 m thick stone walls. These walls are probably remains of a fortification system, which defended the acropolis. The fortification works must be dated to the second half of the 6th century or about its middle. The fortification system of Myrmekion is one of the earliest among those known so far in the North Pontic Area. The discoveries in question amend our views on the Greek colonisation of the Bosporus and of the early history of Bosporan colonies.