The name "Capitolium" is derived from the Latin word "caput," meaning "head" or "summit." According to legend, when the foundations for the temple were being laid, the head of a man was discovered, leading to the hill being called Mons Capitolinus. The Capitolium was considered indestructible by the Romans and was seen as a symbol of eternity.

The Capitoline Hill came to be known as Capitolino in Italian and Capitolium Campidoglio by the sixteenth century CE. It contains few visible ancient ruins because they are mostly hidden by the Medieval and Renaissance palaces (now housing the Capitoline Museums) that surround a piazza, a design created by Michelangelo. The term "Capitolium" is still used in the English word "capitol", and it is believed that Capitol Hill in Washington D.C. is named after the Capitoline Hill.

circa 431 BCE

Sosianus Temple of Apollo Medicus
The Temple of Apollo Socianus, pledged as an offering during a plague in 433 BCE, was dedicated in 431 BCE to the deity Apollo Medicus for his beneficial role in health and healing. The temple was built in an area called Prata Flaminia (Flaminian meadows) where, an Apollinar (or altar to Apollo) dedicated to the worship of the god had been documented since 449 BCE, the surrounding area was settled in 221 BCE with the construction of Circus Flaminius, while new work on the temple was probably carried out during the second century BCE, at the time as the construction of a theatre and a proscenium nearby, thatrical structures built not in masonry but probably in wood.

During the reign of Augustus, the whole area was transformed by the construction of the theatre of Marcellus and the extensive construction project connected with it. The temple was totally rebuilt by Guis Sosio, the former lieutenant of Julius Caesar, hence the source of Sicianus in the temple's name. The new temple was set back towards the north to make room for the theatre and because of the limited space the front set of stairs was replaced by two side staircases. The building, set on a high podium, had six columns of Carrara marble across the front and half columns in stuccoed travertine on the sides and back.

The columns rest on elegant bases characterised by a double rope motif, the shafts have alternately wider and narrower grooves, and the capitals are inspired by the Corinthian style. On the frieze are carved laural branches, the plant sacred to Apollo, suspended between two bucrania (a decorative element made of an ox skull). The pediment was decorated with original Greek sculptures of the fifth century BCE depicting an "Amazonomachy" the legendary battle between Greeks and Amazons in the presence of the goddess Athena. Richly coloured marbles adorned the interior of the cell, which featured an architectural decoration of two overlapping orders marked by columns in African marble and niches of varying forms on the lower lever. Here precious works of art were exhibited, primarily statues by Greek artists and paintings.

Inside the temple the senate gathered to welcome foreign delegations or receive magistrates endowed with Imperium (the power to command). In front of the temple was a fresh water basin known as a perirrantherion in Greek which wasused for ritual ablutions related to purification ceremonies. The three corner columns currently visible were reassembled in1940 CE in honour of Rome's Founder's Day, serving almost as a scenic backdrop for the new road that formed an axis that linked the center of Rome with Via Ostiense and the sea.

circa 296 BCE

Temple of Bellona
The temple on the east side of the Apollo's Temple was built in 296 BCE by Appio Claudio Cieco after a victory over the Etruscans. It was dedicated to Bellona, a warrior divinity of ancient Italian origin. Today all that remains is the core of the podium made with Roman concrete that was used in the reconstruction during the Augustan period (circa 5-15 CE). The temple was of great dimensions with a front staircase leading up to six columns of Luni marble on the short sides and eleven stuccoed travertine columns on the long sides.

Due to its particular location outside the pomerium (sacred area) but very close to the walls, the building was used for special senatorial gatherings where military issues were discussed, such as to whether to grant the honours of a triumph to victorious generals or for meetings with the ambassadors of countries that were either fighting with Rome or were not Roman allies and thus could not take place inside the pomerium.

Outside the temple was the "war column", against which the spear was hurled, an act which according to the Roman ritual, sanctioned the declaration of war to the enemies.

In the Middle Ages, the temple was stripped ofall its marble decoration, all of which was either reused in other buildings or burned in the nearby lime-kiln to obtain lime. The two temples were surrounded on two sides by a small portico built at the same time as the theatre of Marcellus. In the ninth century CE at the rear of the temple of Apollo, a public structure was built, a balneum, or bath which was connected to the diaconate of Sant'Angelo in Pescheria at the Porticus Octaviae (Portico of Octavia).

circa 13 BCE

Theatre of Marcellus
The Theatre of Marcellus (Teatro di Marcello) is an ancient open-air theatre in Rome, Italy, built in the closing years of the Roman Republic. It was named after Marcus Marcellus, a Roman general and statesman who was the nephew of Emperor Augustus. The theatre was built in the late first century BCE and was one of the largest and most impressive theaters in the Roman world. It had a seating capacity of up to 20,000 people and was used for a variety of performances, including plays, music, and gladiator games. The Theatre of Marcellus was built of brick and concrete, and it was decorated with marble and ornate carvings. It was an important part of Roman society and culture, and it was a popular gathering place for citizens of all classes.

The Theatre of Marcellus was built on the site of an earlier theater, the Theatre of Pompey, which was destroyed during the civil wars that followed the death of Julius Caesar. The new theatre was built to honor Marcellus, who was seen as a hero for his military successes and his efforts to restore stability to Rome. The theatre was designed in the Roman style, with a tiered seating area that was surrounded by a series of arches and columns. The stage was located at the bottom of the seating area, and it was surrounded by a series of rooms and corridors that were used by actors and stagehands.

Despite its importance, the theatre fell into disrepair over the centuries and was largely abandoned by the Middle Ages. It was not until the 18th and 19th centuries CE that the theatre was rediscovered and restored to reflect some of its former glory.

circa 10 BCE

Portico of Octavia
The Portico of Octavia (Porticus Octaviae) is an ancient structure in Rome. The colonnaded walks of the portico enclosed the temples of Jupiter Stator and Juno Regina, as well as a library. The structure was used as a fish market from the medieval period up to the end of 19th century CE. The portico was a covered structure with a series of columns that supported a flat roof, and it is known for its beautiful architectural style. The Portico of Octavia has undergone several renovations over the centuries and has been used for a variety of purposes, including as a church and a museum.

circa 120 CE

Insula dell'Ara Coeli
This Capitoline Insula dates to the first two decades of the second century CE. It was built up against the rocky slopes of the Campidoglio, which had been evened off at the beginning of the previous century with the construction of a wall in reticulated brickwork (opus reticulatum). The building came to light during the demolition work in the 1930s CE. The removal of the renaissance and medieval buildings that had spring up at the foot of the Campidoglio revealed the underlying Roman era structures.

Today only four floors remain. The shops (tabernae) on the ground floor lie nine meters below present street level. Wooden steps inside the shop led up to a mezzanine at first floor level. The rooms on the other three floors were for residential use. A fresco (inspect) depicting Christ descended from the cross between the Virgin Mary and Saint John the Apostle adorns the facade of the block of flats. It originally embellished the Church of Saint Rita. The architect Carlo Fontana designed this church in 1665 CE. The church partially incorporated in to its structure the remains of the Roman insula and a Romanesque bell tower. The latter had belonged to the earlier eleventh century CE Church of Saint Biagio de Mercato of in Campitello.

circa 160 CE

Republican Era Portico of Holitorium Forum
The late Republican portico (Portico Repubblicano al Foro Olitorio) was a covered public building located at the south end of the Forum Holitorium in Rome, just outside the Servian Wall. It was built in the fourth century BCE and was connected to a gate, which some believe was a double gate known as the Porta Carmentalis and Porta Triumphalis. The portico had parallel arcades with exterior semi-columns on both sides, but it is only partially preserved today and does not have its ends. The portico consists of two sections, one constructed of peperino on travertine footings and the other made entirely of travertine. Both sections were built in the first century BCE and were used as a monumental entranceway to the city. The portico also connected the Circus Flaminius and the Forum Bovarium, which were both significant landmarks on the triumphal route.

circa

House of Pierleoni
The House of Pierleoni (Casina dei Pierleoni) is a historical building located in Rome, Italy. It was originally built in the 11th century as a fortified palace for the Pierleoni family, who were a wealthy and influential Roman clan. The building has undergone many renovations and additions over the centuries, and today it serves as a cultural center and event space. The Casina dei Pierleoni is known for its beautiful architecture, which blends elements of medieval and Renaissance styles. It is a popular tourist attraction and is often used as a venue for concerts, exhibitions, and other cultural events.