Its precinct was used for diplomatic functions as well as for meetings of the Roman Senate, and contained the Portico of the Danaids, which included libraries of Greek and Latin literature considered among the most important in Rome.

It was situated in the Campus Martius, outside the ceremonial boundary (pomerium) of Rome, since Apollo, whose worship originated in the Greek world, was considered a 'foreign' deity and so unsuitable for a temple within the city.

[3] After securing control over the Roman state through victory in his civil war against Mark Antony, Octavian (known as "Augustus" from 27 BCE) made a political and ideological priority of the embellishment and restoration of Rome's built space.

[10] The Temple of Apollo Palatinus was among the earliest of a series of monuments constructed by Augustus around Rome,[11] and his first major architectural project undertaken independently in the city.

According to the Roman historian Tacitus, Claudius's wife Agrippina the Younger had a secret door installed in the room used for the senate meetings, leading to a hiding-place from which she could listen to them.

[53] The temple may have been systematically dismantled after the fire; pieces of marble from it were possibly reused in the construction of a new building, of uncertain function, on top of the ruined podium at some point in late antiquity.

[54] In the twelfth century, the philosopher John of Salisbury propagated an account that Pope Gregory I (r. 590–604) had destroyed the Library of Palatine Apollo to create more space for Christian scriptures, but his testimony is considered unreliable by modern scholarship.

[74] A Roman temple generally included an enclosed inner part, known as the cella, surrounded by a series of columns (the peristyle) and approached via a porch or vestibule known as the pronaos.

[76] Corinthian capitals have been found among the temple's remains;[38] the columns which supported them are reconstructed to have reached 14 metres (46 ft) in height and have supplied evidence of fluting.

[82] In 1913, the prehistorian Giovanni Pinza suggested that the temple may have faced north, which he considered a better fit with the surviving accounts of its appearance in Roman literature, but his idea was generally rejected.

[93] Depictions of the statue on Roman coinage suggest that its base was decorated with anchors and the prows of ships, linking it to the naval victory at Actium, while its hands held a lyre and a libation bowl.

[7] The Roman polymath Pliny the Elder, writing in the second half of the first century CE, catalogued works of Bupalus and Athenis, two Chian sculptors of the archaic period (c. 800 – c. 480 BCE), on the temple's pediments.

[97] The inclusion of statues by noted Greek artists, especially of the fourth and fifth centuries BCE and the archaic period, came to be almost universal in the temples built or restored by Augustus in Rome.

[7] One of the marble jambs of the doors depicted a Delphic tripod[38] flanked by griffins, with an acanthus, symbolic of Apollo in his capacity as a god of regeneration, springing from it.

[112] Other scenes show the Egyptian goddess Isis trapped between two sphinxes, probably alluding to the defeat of Cleopatra,[113] and human beings worshipping sacred objects.

[114] It has been suggested that a marble sculpture known as the meta ('turning-post'), displayed in modern times in the Villa Albani, may originally have been one of several monumentalised baetyli that stood around the sanctuary.

[119] According to the classicist Bénédicte Delignon, the temple served to establish Apollo as the tutelary deity of Rome and as a representation of Augustus's symbolic refoundation of the city.

[32] In Augustus's political propaganda, it represented the restoration of Rome's 'golden age', a key aspect of Augustan ideology,[120] marked by the end of civil war and the reaffirmation of Roman pietas.

[94] The visual iconography was particularly ideologically charged: though it made no direct references to Augustus, it employed several images and tropes commonly associated with him in contemporary culture.

According to Augustus's autobiography, the Res Gestae, he melted down approximately 80 silver statues of himself that had been offered there by Rome's citizens, sold the resulting metal and used the proceeds to purchase gold tripods in honour of Apollo.

[100] The temple played a significant role in the Secular Games, a religious and artistic festival revived by Augustus in 17 BCE and repeated irregularly thereafter.

[127] On 3 June, the third day of the inaugural games, Augustus and his lieutenant Marcus Vipsanius Agrippa made sacrifices to Apollo and Diana at the temple.

[128] The poet Horace wrote his Carmen Saeculare, a religious hymn, for the occasion: it received its first performance on the same day, sung at the temple by a choir of 27 boys and 27 girls and accompanied by sacrifices to Apollo and Diana.

[1] It was noted by contemporaries as among Rome's most impressive monuments,[27] and described by the historians Velleius Paterculus and Josephus in the 1st century CE as the greatest of Augustus's building projects.

[136] Around 20 BCE, the poet Tibullus wrote an elegy (2.5) commemorating the appointment of Marcus Valerius Messalinus as a priest of Apollo with responsibility for inspecting the Sibylline Books stored at the temple.

[138] The newly intensified religious significance of the Palatine Hill also featured in its presentation in the eighth book of Virgil's Aeneid, composed between 29 and 19 BCE, in which the king Evander walks Aeneas around the future site of the temple;[10] later in Aeneid 8, the Battle of Actium is reconstructed as a theomachic contest on the Shield of Aeneas, and Augustus's triple triumph of 29 BCE is anachronistically imagined as having taken place at the temple.

[100] In modern times, only the cement core of the temple's podium, measuring 19.2 by 37.0 by 4.7 metres (63.0 by 121.4 by 15.4 ft),[52] survives,[38] as well as isolated architectural fragments including blocks from the cella.

[82] The architect Henri Deglane, a member of the French School at Rome, accepted this identification in his 1885–1886 reconstruction of what he called the "Palace of the Caesars" on the Palatine Hill.

[148] In 1910, Giovanni Pinza studied the concrete used in the temple and concluded that it was early Augustan in date, being similar to that used for the Mausoleum of Augustus, completed in 28 BCE.

[156] Between 2009 and 2013, Zink also documented the architectural remains in an area south-west of the temple, revealing a building dating to the archaic period (that is, between the sixth and early fifth centuries BCE), which he posited to have been a small shrine.