The archaeological site of Philippi is located west of the modern town of Krinides, on the provincial road connecting Kavala with Drama. The most important monuments in the area are the city walls, the acropolis, the theatre, the forum, Basilica A, Basilica B, and the Octagon.
The 3.5-kilometre-long walls begin at the fortified acropolis on the hilltop and surround the foot of the hill and part of the plain (first building phase: Philip II, mid-fourth century BC; second building phase: Justinian I, 527 - 565 AD). Inside the acropolis is a Late Byzantine tower.
The theatre, which was probably built by King Philip II in the mid-fourth century BC, was thoroughly remodelled in the second and third centuries AD in order to accommodate Roman spectacles.
The Roman forum, the city's administrative centre in the Roman period, was a unified complex of public buildings positioned around a central square, with two monumental temples at the northeast and northwest. The large paved road that runs north of the forum has been identified as the ancient Via Egnatia.
Basilica A (end of fifth century AD) is a large three-aisled basilica, 130 metres long and 50 metres wide, with a transept, a square atrium, a gallery over the aisles and narthex, and an unusual phiale. Fragments of the luxurious pavement and part of the ambo are preserved in the central aisle. The impressive wall paintings in the chapel's anteroom imitate opus sectile decoration.
Basilica B (ca. 550 AD) is a three aisled basilica with a narthex and annexes to the north and south (phiale and vestry). The almost square central aisle was covered by a dome supported on large pillars, and the sanctuary was vaulted. The sculptural decoration is clearly influenced by Constantinopolitan art.
The so-called Octagon was the episcopal church of Philippi. The church proper presents three building phases (late fourth/early fifth century - mid-sixth century AD). It replaced an earlier smaller church dedicated to Saint Paul (early fourth century), built on the site of a Late Hellenistic tomb-her?on. The complex also comprises a phiale, a baptistery, a bathhouse, a two-storied Episcopal residence, and a monumental gateway towards the Via Egnatia.
The rectangular building (measuring 27 x 10m) that was discovered south of the Forum of the Roman city, with a portico that consisted of a colonnade of six Corinthian columns on its fašade, is being identified by its architectural layout and the inscriptions which were found, as the Roman commercial market (macellum). The complex consisted of a central columned court, right and left of which there were shops.
The complex of the commercial market is separated from that of the Forum with a wide road, 9m wide, the commercial street. It is a building of the Antonines period (second half of 2nd century AD), contemporary with the Forum. In the mid-6th century AD, most of it was destroyed to its foundation in order to create the space that was necessary for the construction of the Basilica B. Only its northern part was kept with the six-column colonnade, which was incorporated by the Byzantine architect into the Basilica forming a monumental entrance to its north aisle.