There were many civilizations during, "classical antiquity". Should we focus primarily on the Greeks? If so, why then should we exclude their counterparts, such as, the Romans, the Persians, the Phoenicians, the Egyptians, as well as many others?
If one wants to solely focus on the origins of Classical Greek Antiquity, then that is another question altogether.
The earliest evidence of Greek civilization dates back to the town of Mycenae in the Northeastern Peloponnese-(about 100 miles West of Athens). Around 1600 BC/ BCE-(in the wake of the massive volcanic explosion on the island of Santorini, as well as the gargantuan Tsunami which followed and subsequently, destroyed the Minoan civilization on Knossos in Crete), Mycenae emerged as a major power. The Greco-Mycenaeans sailed to a devastatingly beleaguered Crete and essentially, Hellenized the island and much of its surviving population-(assuming, that the Minoan Cretans were not originally of Hellenic descent). However, the Greco-Mycenaeans also absorbed some elements of Minoan Cretan culture as well.
Mycenae, was the first Greek city-(1000 years before the rise of Athens and many other Greek city-states). It is the oldest city in Greece and is perhaps the 2nd oldest city in Europe-(or Urban settlement) behind Knossos. Today of course, Mycenae, like Knossos, are archaeological sites and are currently, very distant from their urban heyday.
The proliferation of Greco-Mycenaean culture can be found throughout Greece-(primarily in the Peloponnese, the Ionian islands of Western Greece, the
aforementioned Crete and yes, their influence can be found in Athens). About 1000 years before the construction of The Parthenon, the Mycenaeans built a fort and when touring the Parthenon, as well as examined very closely, one can find scattered remnants of the Mycenaean fort.
Homer's famed, "Iliad", is, to a great extent, a Mycenaean historical narrative. When we study "The Iliad", it is usually read from a poetic or literary context. However, if read and studied from a historical and archaeological context, the central Greek characters include, Mycenaeans, specifically, the King of Mycenae, Agamemnon. The Greek soldiers and Officers fighting in the REAL-(and not mythologized) Trojan War during the 1190's BC/BCE, were primarily comprised of Mycenaeans-(along with Spartans, as well as Greeks from other regions).
Mycenaean Greece was born around 1600 BC/BCE and flourished for about 500 years. However, due to various invasions from other parts of Europe and Asia, as well as perhaps for other (presently unknown) reasons, Mycenae vanished almost
overnight. From 1100 BC/BCE-800 BC/BCE, a so-called, "Dark Ages" followed and was widespread throughout Greece. By 800 BC/BCE, the Poet Homer enters and "The Iliad" was born on the Aegean island of Chios.
If one looks at Greco-Mycenaean culture, one can find an impressively well preserved ancient city, followed by a collection of jewelry and pottery
throughout the ancient site-(though most of its collection is in the National Museum in Athens). The city's architecture appears to have little outside influence and looks to be quite original. Admittedly, it may not be as impressive looking as other ancient cities, such as, Pompeii, Ostia, the Forum in Rome or The Agora in Athens. However, Mycenae's impressiveness is not necessarily related to its aesthetics, rather, Mycenae's impressiveness is rooted in its longevity and fine preservation.