Presently, the Agora of Athens stands as an archaeological site situated beneath the north-western incline of the Acropolis. The term "agora" denotes a gathering of individuals and, by extension, designates a place where such gatherings take place. In contemporary Greek, the term is commonly understood as a "marketplace."

Nearly every ancient and contemporary city incorporates a designated space known as an agora, and the Agora of Athens, situated at the center of the city, served various purposes throughout its existence spanning nearly three millennia. It functioned as a hub for assemblies, commerce, and even residential activities. Consequently, the area underwent numerous cycles of construction, destruction, and reconstruction. Through extensive excavations, the layers of history have been carefully unearthed, revealing the significant roles played by the Agora during different periods, ranging from the Archaic era to the Greco-Roman and Byzantine times.

circa 550 BCE

Tholos
The Tholos, located within the Agora, is a significant public structure characterized by its circular shape, six interior columns, and an added entrance called the propylon in the eastern part, constructed during the first century BCE. It served as the headquarters for the fifty prytaneis, who formed the executive committee of the Boule (council) and held their position for approximately thirty five or thirty six days. Afterward, they were replaced by prytaneis from a different tribe, ensuring that representatives from all ten tribes eventually participated in the administration throughout the year. The prytaneis in office would dine in the Tholos, with around one-third of them (specifically seventeen individuals) spending the entire night in the building, guaranteeing the presence of responsible officials at all times.

Within the Tholos, the official weights and measures of the Athenian state were stored. The structure was constructed on top of an existing building complex dating back to the mid-sixth century BCE, which served a similar functional purpose. Its use ceased around 400 CE.

circa 520 BCE

Altar of the Twelve Gods
The altar of the twelve gods stood in the center of a rectangular sacred enclosure, with a paved floor and a stone superstructure of low vertical slates and orthostates; those flanking the entrances bore carved representations. According to Thucydides, it was built under Peisistratos, grandson and namesake of the famous tyrant. It was dedicated probably to the twelve gods of the Olympos. The altar, standing as it does next to the Panathenaic Way and at the intersection of several important traffic arteries, was a celebrated place for refuge. It is from the altar that milestones within the city record their distances. It was kept in repair until the fourth century BCE, but was destroyed in the third century CE. Since the opening of the electric railway in 1891 CE, only the south-west corner (inspect) of the ancient altar is visible.

circa 450 BCE

Temple and Altar of Ares
Doric peripteral temple, with pronaos (for-temple), inner shrine (cella) and opisthanaos (rear temple). It was contemporary with and almost identical to the temple of Hephaistos on the Kolonos Agoraios Hill. Its monumental, stepped marble altar (inspect) was built in the fourth century BCE. Originally the two monuments stood elsewhere, probably in the Deme of Acharnai or, according to a later view, in Pallene. At the end of the first century BCE, at the command of the Roman emperor Augustus, the temple and the atar were disassembled, transferred to the agora and reassembled. In order to assure a correct assebly, masons inscribed its stones with identifying marks. The foundations of the temple were embanked into the earth for protection and therefore its ground-plan is conventionally indicated. Marble pieces from its superstructure are concentrated in the west part; decorative sculpture from the temple is on display in the Museum of the Ancient Agora. Both mnuments were destroyed during the Herulian invasion.

circa 430 BCE

Monument of the Eponymous Heroes
The monument of the Eponymous Heroes was a pedestal, approx. sixteen meters long, enclosed by stone posts connected to one another by three wooden beams. It bore the bronze statues of the mythical heroes of each of the ten Athenian tribes, divisions into which, for administrative and political reasons, Kleisthenes in 508 BCE organized the citizens of Athens. A fluctuation in the number of tribes over the years necessitated the removal or addition of statues. On the sides were hung the wooden boards with announcements meant for the citizens conscripted into the army, civic honorary distinctions, forthcoming lawsuits. The original location of the monument was most likely somewere else in the agora, probably at the west end of the Middle Stoa.

The ten heroes were; Erechtheus, Aegeus (Theseus' father), Pandion (usually assumed to be one of the two legendary kings of Athens, Pandion I or Pandion II), Leos, Acamas (son of Theseus), Oeneus, Cecrops II, Hippothoon, Aias (Ajax), Antiochus (a son of Heracles).

circa 415 BCE

Temple of Hephaestus
The Temple of Hephaestus, previously known as the Theseion or "Theseum" erroneously, is an exceptionally preserved ancient Greek temple devoted to Hephaestus. It stands mostly undamaged to this day. This temple follows the Doric peripteral style and is situated on the north-western side of the Agora of Athens, atop the Agoraios Kolonos hill. Between the seventh century CE and 1834 CE, it functioned as the Greek Orthodox church of Saint George Akamates. Its remarkable state of preservation can be attributed to its diverse history of utilization.

circa 175 - 150 BCE

Middle Stoa
The Middle Stoa is the largest building in the Agora, 147 meters wide and 17.5 meters deep, oriented east-est, with a Doric colonnade on each of its four sides. It is assumed that at the two corners of the monument the intercolumniation were covered with high, thin panelling like that of the interior Ionic colonnade, which separated the stoa into two passageways of equal width. The stoa was built of poros stone. Only the metopes of the frieze were of marble, together with the terracotta sima they boree a painted decoration. In the eastern section, steps and three columns-drums are preserved in their original position. Visible on the western side are its solid foundations of red conglomerate stone. In Roman times the flat terrace at its north was used as the shortest way of crossing the Agora from east to west. It was destroyed by fire in 267 CE.

circa 15 BCE

Odeon of Agrippa
The odeon of Agrippa, a grand and luxurious building designed for musical performances, is known in the ancient sources as the "odeion", the "Kerameikos" theatre or the "Agrippeion" after its donor, Marcus Vipsanius Agrippa, son in law to the emperor Augustus. The central part of the building,which rose, as if a separate structure, above a surrounding stoa, included an oblong rectangular stage, a semi-circular "orchestra" and an auditorium built like an amphitheatre, with space foraround 1000 people. The entrance for the audience was formed, on the southern side of the building, by the terrace of the Middle stoa, while a small tetrastyle propylon on the north side led directly to the stage area. The building originally had a pitched roof, without interior support, which collapsed around 150 CE. Then the building was reconstructed with the addition of a transverse wall that reduced the seating capacity almost by half. The north facade took the form of a stoa, the eistyle of which supported six colossal statues of Tritons and the Giants. Four of them later adorned the gymnasium of the "Palace of the Giants", which was built over the remains of the odeon. The building was destroyed by fire in 267 CE, in the Herulian invasion.

circa 410-530 CE

"Palace of the Giants"
The so-called "Palace of the Giants", impressive in itssize,included a great section of the central area of the ancient agora, covering older buildings such as the odeion of Agrippa and parts of the Middle Stoa and of the South Stoa II. It contained a bathing establishment surrounded by several rooms, two colonnaded coutyards, and a garden at the southern side. In all, the complex covered 13,500 square meters. Its entrance facing the Panathenaic Way was monumental, with a triple opening and four pillars on which were placed the colossal statues of the Tritons and the Giants from the odeon. Originally the building was considered a gymnasium, but it was probably a palace, seat of a high ranking administrative official.

circa 140 CE

Hadrianic Aqueduct
During his reign, the Roman emperor Hadrian (117 - 138 CE) undertook various construction projects in Athens that had a lasting impact. Among these projects was the Hadrian's aqueduct, which is believed by some scholars to have been intended to serve the newly developed Hadrianic quarter, also known as the 'City of Hadrian' or Hadrianopolis, located southeast of the ancient city. This quarter encompassed the present-day areas of Zappeio and extended from Kalimarmaro to the Parliament building.

The construction of the Hadrian aqueduct began in 125 CE under the emperor's orders and was completed fifteen years later, during the reign of Antoninus Pius, in 140 CE. The aqueduct primarily consisted of an underground tunnel with a masonry channel, stretching for almost 20 kilometers. Notably, the aqueduct was designed not only to collect water from its main source but also to gather additional quantities from other sources along its route. To achieve this, auxiliary water carriers and supplementary tunnels were constructed, bringing water from springs located around Halandri, Kokkinara, and Kithara Monomati.

circa 950 CE

Church of the Holy Apostles of Solakis
It is situated partly over a second century CE Roman era Nymphaeum. The original floor plan of the church was that of a cross, with apses on the four sides and a narthex on the western side. Four columns supported the dome. The altar and the floor were of marble. The disposition of the outer walls show "cufic" decorative patterns of eastern origin. Four building phases have been identified from the repairs and reconstruction works over the years. Among the many medieval monuments known to have existed in the agora, it is the only one preserved to date. It was restored to its original form in 1954-1957 CE. The few surviving wall paintings in the central aisle are of the seventeenth century CE. Wall paintings from other nearby churches have been placed elsewhere in the church.