The dawn of the Classical period was marked by the Persian Wars, which didn't leave Delphi unscathed, despite the pro-Persian attitude that the sanctuary seems to have held, with its ominous oracles to the Greek cities fighting against the Persians. According to Herodotus, in 480 B.C. the Persians, after their victory at Thermopylae, on their way towards southern Greece, sent a military unit to Delphi, in order to loot the sanctuary. It is reported that the inhabitants of the region sought refuge in the Corycean cave, which was difficult to locate. However, the Persian army never reached the sanctuary: they were driven away by two local heroes, namely Phylakos and Autonoos. Tradition has it, however, that rocks from two summits of Parnassus fell and blocked the way to the invading Persians, killing many of them.
Delphi remained autonomous until 448 B.C, when the Phocaeans, aided by the Athenians, attempted to annex the city to the Phocaean League. The Spartans’ reaction to this attempt resulted in the Second Sacred War. The Phocaeans, however, managed to gain control over Delphi, establishing a status quo which was maintained until 421 B.C. Later, in the course of the Peloponnesian War and during the (unfavourable for the Athenians) Peace of Nicias, Delphi regained its freedom. It maintained its independence until 356 B.C., when the Phocaeans captured the city in retaliation for a heavy fine that the Amphictyonic Convention had imposed on them. This episode triggered the Third Sacred War and instigated the involvement of Philip II of Macedonia in Central Greece politics. Finally, the Fourth Sacred War, of relatively short duration, broke out in 339 B.C., instigated by the actions of the Locrians of Amphissa; the war eventually led up in the Battle of Chaeroneia (338 B.C.) and the final subjugation of the rest of Greece to Philip and the Macedonians.

The evolution of the sanctuary in the classical period
Important and famous buildings were erected in Delphi during the classical period. Along the Sacred Way several buildings were placed, such as the Treasury of the Athenians, the Portico of the Athenians, the Treasury of the Megarians, the Treasury of the Thebans etc. The temple of Apollo, situated at the end of the Sacred Way, was rebuilt in ca.330 B.C. (late classical period), whereas the altar of the temple (altar of the Chians), which had been built around 475 B.C., was restored in order to match the temple architecturally. The area around the temple was decorated by artistic masterpieces, such as the Monument of Daochos, situated in front or (most probably) within the Treasury of the Thessalians. Within the sanctuary of Athena Pronaia the Tholos and the Doric Treasury were built and, slightly later, the limestone temple. Towards the end of the classical period the first buildings of public and athletic character were constructed, such as the Gymnasium, between the sanctuary of Athena and the Castalia Spring, and the Stadium, above the temple of Apollo.
Finally, during the classical period ex-votos of high artistic value were put up at Delphi. Some of the preserved offerings allow us a glimpse into the wealth that had been accumulated in the city and the sanctuary after the Persian Wars. The famous Charioteer, one of the masterpieces of the so-called “severe style” which marks the transition from the archaic to the classical period, as well as smaller bronze offerings, such as the incense burner in the form of peplophoros supporting a cauldron, the Flute Player and the pair of athletes, which have been found within the dump pit of the Sacred Way, are but a few specimens of early classical art. Unfortunately, many offerings were destroyed during the Third Sacred War, whereas others were transported to Rome after the Roman conquest. It seems, however, that in the 2nd century A.D. there were still several statues extant in situ, according to the testimonies of Pausanias and Plutarch. The latter describes in detail, for example, the sculpted group consisting of 37 statues that the Lacedaemonians had dedicated after the battle at Aegos Potamoi (405 B.C.), their ultimate victory during the Peloponnesian War. Apparently, the Lacedaemonians followed a practice established by the Athenians in 460 B.C., when they assigned to Pheidias the task to create a sculpted group of 13 statues using metal from the booty of the Persian Wars. Great sculptors, such as Ageladas from Argos and Onatas from Aegina were among the artists who adorned with their works the sacred sanctuary of Apollo.
At the end of the classical period, a time when the army of Alexander the Great was already marching in the East, another masterpiece marks the transition towards the Hellenistic art: the “Three Dancers”, the sculpted complex of three maidens which seems to stem from a 10-meter tall column wrapped in acanthus leaves, supporting an elaborate tripod within which the “omphalus” apparently stood The column was set up on the occasion of the Pythaid of 330-325 B.C. Recent interpretation has shown that the dance-like position of the hands was actually a way to support the tripod; the three female figures were probably depicting the three daughters of the mythical Athenian king Cecrops