Apollo in the context of "Apollo Lyceus"

Religious practices in ancient Greece encompassed a collection of beliefs, rituals, and mythology, in the form of both popular public religion and cult practices. The application of the modern concept of "religion" to ancient cultures has been questioned as anachronistic. The ancient Greeks did not have a word for 'religion' in the modern sense. Likewise, no Greek writer is known to have classified either the gods or the cult practices into separate 'religions'. Instead, for example, Herodotus speaks of the Hellenes as having "common shrines of the gods and sacrifices, and the same kinds of customs".

Most ancient Greeks recognized the twelve major Olympian gods and goddesses—Zeus, Hera, Poseidon, Demeter, Athena, Ares, Aphrodite, Apollo, Artemis, Hephaestus, Hermes, and either Hestia or Dionysus—although philosophies such as Stoicism and some forms of Platonism used language that seems to assume a single transcendent deity. The worship of these deities, and several others, was found across the Greek world, though they often have different epithets that distinguished aspects of the deity, and often reflect the absorption of other local deities into the pan-Hellenic scheme.

The Delian League was a confederacy of Greek city-states, numbering between 150 and 330, founded in 478 BC under the leadership (hegemony) of Athens, whose purpose was to continue fighting the Persian Empire after the Greek victory in the Battle of Plataea at the end of the Second Persian invasion of Greece. The League functioned as a dual—offensive and defensive—alliance (symmachia) of autonomous states, similar to its rival association, the Peloponnesian League. The League's modern name derives from its official meeting place, the island of Delos, where congresses were held within the sanctuary of the Temple of Apollo; contemporary authors referred to the organization simply as "the Athenians and their Allies".

While Sparta excelled as Greece's greatest power on land, Athens turned to the seas, becoming the dominant naval power of the Greek world. Following Sparta's withdrawal from the conflict with Persia, Athens took the lead of the Hellenic alliance accompanied by several states around the Aegean and the Anatolian coast. The Delian League was formed as an anti-Persian defensive association of equal city-states seeking protection under Athens, as the latter wished to extend its support towards the Ionian Greek colonies of Anatolia. The alliance held an assembly of representatives in order to shape its policy, while members swore an oath of loyalty to the coalition. By the mid-fifth century BC, it had developed into a naval imperial power, conventionally called the Athenian Empire, where Athens established complete dominion and the allies became increasingly less autonomous. The League successfully accomplished its principal strategic goal by decisively expelling the remaining Persian forces from the Aegean. As a result, Persia would cease to pose a major threat to Greece for the following fifty years.

Delos or Dilos (/ˈdiːlɒs/; Greek: Δήλος [ˈðilos]; Attic Greek: Δῆλος Dêlos, Doric Greek: Δᾶλος Dâlos), is a small Greek island near Mykonos, close to the centre of the Cyclades archipelago. Though only 3.43 km (1.32 sq mi) in area, it is one of the most important mythological, historical, and archaeological sites in Greece. The ongoing excavations in the island are among the most extensive in the Mediterranean, and many of the artifacts found are displayed at the Archaeological Museum of Delos and the National Archaeological Museum of Athens.

Delos had a position as a holy sanctuary for a millennium before Olympian Greek mythology made it the birthplace of Apollo and Artemis. From its Sacred Harbour are visible the three conical mounds that have identified landscapes sacred to a goddess (presumably Athena). Another site, retaining its Pre-Greek name Mount Cynthus, is crowned with a sanctuary of Zeus.

Zeus (/zjuːs/, Ancient Greek: Ζεύς) is the chief deity of the Greek pantheon. He is a sky and thunder god in ancient Greek religion and mythology, who rules as king of the gods on Mount Olympus.

Zeus is the child of Cronus and Rhea, the youngest of his siblings to be born, though sometimes reckoned the eldest as the others required disgorging from Cronus's stomach. In most traditions, he is married to Hera, by whom he is usually said to have fathered Ares, Eileithyia, Hebe, and Hephaestus. At the oracle of Dodona, his consort was said to be Dione, by whom the Iliad states that he fathered Aphrodite. According to the Theogony, Zeus's first wife was Metis, by whom he had Athena. Zeus was also infamous for his erotic escapades. These resulted in many divine and heroic offspring, including Apollo, Artemis, Hermes, Persephone, Dionysus, Perseus, Heracles, Helen of Troy, Minos, and the Muses.

Pythia (/ˈpɪθiə/; Ancient Greek: Πυθία [pyːˈtʰíaː]) was the title of the high priestess of the Temple of Apollo at Delphi in central Greece. She served as its oracle and was known as the Oracle of Delphi. Her title was sometimes historically glossed in English as the Pythoness.

The Pythia was established at the latest in the 8th century BC (though some estimates date the shrine to as early as 1400 BC), and was widely credited for her prophecies uttered under divine possession (enthusiasmos) by Apollo. The Pythian priestess emerged as pre-eminent by the end of the 7th century BC and continued to be consulted until the late 4th century AD. During this period, the Delphic Oracle was the most prestigious and authoritative oracle among the Greeks, and she was among the most powerful women of the classical world. The oracle is one of the best-documented religious institutions of the classical Greeks. Authors who mention the oracle include Aeschylus, Aristotle, Clement of Alexandria, Diodorus, Diogenes, Euripides, Herodotus, Julian, Justin, Livy, Lucan, Nepos, Ovid, Pausanias, Pindar, Plato, Plutarch, Sophocles, Strabo, Thucydides, and Xenophon.

Delphi (/ˈdɛlfaɪ, ˈdɛlfi/; Greek: Δελφοί [ðelˈfi]), in legend previously called Pytho (Πυθώ), was an ancient sacred precinct in central Greece. It was the seat of Pythia, the major oracle who was consulted about important decisions throughout the ancient classical world. The ancient Greeks considered the centre of the world to be in Delphi, marked by the stone monument known as the Omphalos of Delphi. The term omphalos was the Greek word for "navel".

According to the Suda, Delphi took its name from the Delphyne, the she-serpent (drakaina) who lived there and was killed by the god Apollo (in other accounts the serpent was the male serpent (drakon) Python).

In ancient Greek religion and mythology, the twelve Olympians are the major deities of the Greek pantheon, commonly considered to be Zeus, Poseidon, Hera, Demeter, Aphrodite, Athena, Artemis, Apollo, Ares, Hephaestus, Hermes, and either Hestia or Dionysus. They were called Olympians because, according to tradition, they resided on Mount Olympus.

Besides the twelve Olympians, there were many other cultic groupings of twelve gods.

In ancient Greek religion and mythology, Artemis (/ˈɑːrtɪmɪs/; Ancient Greek: Ἄρτεμις) is the goddess of the hunt, the wilderness, wild animals, transitions, nature, vegetation, childbirth, care of children, and chastity. In later times, she was identified with Selene, the personification of the Moon. She was often said to roam the forests and mountains, attended by her entourage of nymphs. The goddess Diana is her Roman equivalent.

In Greek tradition, Artemis is the daughter of Zeus and Leto, and twin sister of Apollo. In most accounts, the twins are the products of an extramarital liaison. For this, Zeus's wife Hera forbade Leto from giving birth anywhere on solid land. Only the island of Delos gave refuge to Leto, allowing her to give birth to her children. In one account, Artemis is born first and then proceeds to assist Leto in the birth of the second twin, Apollo.

The Temple of Apollo, also known as Apollonion, (Greek: Ἀπολλώνιον, romanized: Apollṓnion) was a major part of the Panhellenic religious sanctuary located in Central Greece at Delphi. The temple and sanctuary at large were dedicated to one of the major Greek deities, Apollo, the god of archery, music, light, prophecy, the arts, and healing. There have been several temples built at Delphi throughout the history of the site, though the visible ruins seen in modernity are those of the temple built in the 4th century B.C.E. before its destruction under the orders of Theodosius I in 390 C.E.. During antiquity, the temple was home to the famous Greek prophetess the Pythia, or the Oracle of Delphi, making the Temple of Apollo and the sanctuary at Delphi a major Panhellenic religious site as early as the 8th century B.C.E., and a place of great importance at many different periods of ancient Greek history. References to Delphi, the sanctuary, the temple, and the prophecies of the Pythia are made throughout ancient Greek mythology and historical accounts from the periods of its use.