The most important Greco-Roman remains on the island, and one of the most important remains of all Greek antiquity is undoubtedly the Law Code of Gortyn. The code, which is still in Gortyn, Kainourio, is written in Greek (Doric) dialect and dates from the first half of the fifth century B.C., making it the most ancient law code known in Greek civilization.

The ancient city of Gortyn in Messara, south of Iraklion, had been in existence from Minoan times but it became particularly strong after the seventh century B.C. In the second century B.C. it defeated Festos and was in continuous war with Knossos or Lyttos. It had two harbours: one in Matala and another in Lendas. The Law Code of Gortyn (in the Odion), the temple of the Apollo Pythios, and the seventh century B.C. temple of Athena on the Acropolis are remains from the Greek era.

Gortyn became the capital of Crete during the Roman era (after 65 B.C.). Extensive Roman remains exist in the area. The Praetorium was the palace of the Roman governor of Crete where many marble columns with capitals of Ionic and Corinthian style may still be seen at the extensive site.

The city of Lato near the village of Kritsa, Lassithi, is probably the most thoroughly excavated Greek city of Crete. It was founded in the seventh century B.C. and destroyed about 200 B.C. Its harbour was in present-day Agios Nikolaos. Lato is located on the top of a hill with an exceptional view of the area around Agios Nikolaos and Mirabelo Bay. The theatre, the agora, the Prytanion, a temple and an altar are among the most important remains.

The site of ancient Aptera in Kydonia, is located near Chania at the top of a hill with a remarkable view of Souda Bay to the north and the Lefka Ori to the south. Aptera was an important Greek city state by the seventh century B.C. The impressive city walls and a temple from the second century B.C. are still visible today. Aptera was also a very significant Roman site with fragment remains of huge Roman cistern complexes, as well as a theatre and other extensive Roman ruins.

The site of Eleftherna was occupied from Minoan times. It became one of the most important Greek cities from the tenth century B.C. An ancient Hellenist bridge still exists at the site, although it is difficult to approach. Massive city walls have also been iscovered as well as a sanctuary from the Greek period. Eleftherna was also an important Roman city. Enormous walls from the acropolis are visible.

The ancient city of Lissos is located near Sougia, Selino and was a significant religious site for the rest of Crete, analogous to Delfi. The remains of a fourth or third century B.C. small Greek temple with an interesting geometric design and a polychrome mosaic floor has been excavated, in addition to many statues from that period. The site was used in Roman times as well, and an extensive Roman cemetery has been discovered.

There are many other Greek and Roman sites on the island but only minor excavation of them has been done so far. The Greek site of ancient Rizinia, on a hill near Prinias, Malevizi, shows expansive remains of the Hellenistic era, and has a spectacular view of the lower parts of Iraklion up to the Lassithi Mountains. The Greek site of Lyttos, on a hill near Xidas, Pediada, has some excavated remains of the Hellenic city and commanding views of the Lassithi Mountains. In Vrises, Apokoronas there is a Greco-Roman bridge. There are Roman remains in Polirinia in western Crete and in Limin Hersonisou there are harbour remains and a mosaic fountain from the Roman era.