Rising above the center of the Eternal City is the Mons Capitolinus. This promontory is situated between the Forum Romanum to the east and the Campus Martius to the north and west. At its highest southern point stands the most sacred site in all of Rome, The Templum Iovus Optimus Maximus, also known as the Capitoline Temple of Jupiter. The temple honors the Capitoline Triad of deities; Jupiter, called "dies pater" or Shining Father, his wife Juno, Queen of the Gods and daughter Minnerva, Goddess of Wisdom. The Temple was famous around the Roman world and was copied in provinces as far away as Britannia and Africa. The Mons Capitolinus is truly the spiritual heart of the mighty Roman Empire.

Jupiter et Thétis

The temple foundation is said to have been initiated by the
fifth Tarquin King, Lucius Tarquinius Priscus, but later
completed by Rome's last Tarquin King, Lucius Tarquinius
Superbus. The Temple of Jupiter was completed in 509 BCE,
but then later destroyed by lightning and fire on three different
occasions. Each time it was destroyed it was rebuilt in a much
grander style of opulence than in its previous existence. The
last reconstruction of the temple was completed by the
Emperor Domitian in 82 AD.

At the Mons Capitolinus northern most point lies the Arx, the
northern peak of the Mons Capitolinus. This northern
prominence is the site on which stands the Citadel of Rome
and the augur's observation post. The Citadel is the mightiest
stronghold in all of Rome and has held against numerous
enemy assaults for hundreds of years. Since it's early inception
the Mons Capitolinus has been the preeminent seat of the
municipal government and the unchallenged symbol of
Roman authority. Above the Roman Forum on the
southeastern side of the hill is the Tabularium in which is
maintained the bureaucratic offices of the state and all official
records of Rome.

The infamous Tarpeian Rock, a traditional place of execution,
lies just below the Temple of Jupiter Capitolinus to the south
and many a condemned criminal has been thrown to their
death on the rocks below. The Tarpeian Rock receives it's name
from Tarpeia, the traitorous vestal virgin and daughter of
Spurius Tarpeius, Commanding General under Romulus at the
Citadel. Ancient legend tells of Tarpeia's treachery. She
allowed the Sabine forces inside the walls in exchange for
whatever they had on their arms, hoping for gold bracelets and
other items of value. As the Sabine entered into the fortifications
they crushed her with their shields, which were in fact on their
left arm. Her ashes were scattered on the Tarpeian Rock which
now bears her name.

Other famous events have taken place here as well.
Gaius Julius Caesar suffered a chariot accident during his
Gallic War Triumphal Proceesion in 45 BCE, clearly an omen
indicating the wrath of Jupiter for his actions during the Civil Wars.
In an effort to avert this unlucky augury he approached the hill
and Jupiter's Temple on his knees. Six months later he was
assassinated in Pompey's Theatre by a conspiracy of patrician
senators who opposed his ambitions. These same conspirators,
along with Marcus Junius Burtus, fled to the Temple
of Jupiter Capitolinus after Caesar's assassination and
barricaded themselves there until all danger from the angry
Roman mob had passed.

In Virgil's last epic work, the Aeneid, he refers to a closely
guarded vault beneath the Capitoline Temple of Jupiter where
once were held the renowned Books of the Sibylline. These
books of prophecy were faithfully consulted by the Quindecemviri
(council of fifteen) on all occasion of earthquakes and other
looming disasters. History records that the Apollonian sibyl
who resided by the spring at Cumae originally offered
Tarquinius Superbus nine books of oracular utterances in Greek
hexameters. The price being too high, Tarquinius rejected the offer,
only to learn that she was burning the books of wisdom one
by one. When the sibyl shrewdly offered the remaining three
books for the same exorbitant sum as the original nine, he
paid the price, and the books were preserved until the
disastrous fire which incinerated the Capitol in 83 BCE.

The Capitiolium towers over the Roman Forum and its position of
preeminence in the history of Rome remains secure.

As Platner & Ashby's survey of
ancient Rome notes, There were
three cellae side by side. That in
the middle was dedicated to Jupiter
and contained a terra cotta statue of the god, with a thunderbolt in his right
hand, said to have been the work of
Vulca of Veii, the face of which was
painted red on festival days...
The character of this statue, and of the rest of the decoration of the
temple, is clear from the life-size figures, recently discovered at Veii,
belonging to a group representing the stealing by Heracles of a stag sacred
to Apollo. The chamber on the right
was dedicated to Minerva ...and that
on the left to Juno. Probably there
were statues also in these two chambers, and each deity had her own altar.
(Varro ap. Serv. Aen. iii.134)

The statue of Jupiter was clothed with a tunic
adorned with palm branches and Victories (tunica palmata),
and a purple toga embroidered with gold (toga picta,
palmata), the costume afterwards worn by Roman generals
when celebrating a triumph...The entablature was of
wood, and on the apex of the pediment was a terra cotta
group, Jupiter in a quadriga, by the same Etruscan artist as the
statue in the cella...This was replaced in 296 BCE by another,
probably of bronze (Liv. x.23.12). There is no doubt that
pediment and roof were decorated with terra cotta figures,
among them a statue of Summanus 'in fastigio' (perhaps
therefore an acroterion), the head of which was
broken off by a thunderbolt in 275 BCE . In 193 BCE the
aediles M. Aemilius Lepidus and L. Aemilius Paullus placed
gilded shields on the pediment (Liv. xxxv.10).

At all periods, the hill was less an inhabited part of the city than a
citadel and religious centre. It was successfully defended against
the Gauls when they invaded Rome in 390 BC. Here the Consuls
sacrificed at the beginning of each year and provincial
governors took vows before going to their provinces; a sacrifice
here was the culmination of Roman generals celebrating
their Triumphs.

The original Temple, then some 600 years old, measured almost
200 feet by 180 feet. The Temple was first bunrt down in 83 BCE,
under the wars during the dictatorship of Sulla. The new
temple of Q. Lutatius Catulus was renovated and repaired by
Augustus. It again was burnt down during the course of
fighting on the hill in AD 69, when Vespasian battled to enter the
city as Emperor. The last rebuilding was undertaken by
Vaspasian's second son and heir after Titus, Emperor Domitian.

On the northern summit of the hill, the Arx, lies the temple of Juno
Moneta (344 BCE) and there as well stands the Auguraculum
or augur's observation post, a small grassy area complete with
primitive hut which overlooks the Forum. On the area between
the two hills of the Capitol, known as the inter duos lucos, lies the
temple of Veiovis (192 BCE) and the asylum associated with
Romulus. The east face of the hill overlooking the Forum is
occupied by the massive structure, The Tabularium. The
approach road from the Forum still exists, known as the Clivus
Capitolinus.

Source materials:
Platner & Ashby's - A Topographical Dictionary of Ancient Rome

Museo della Civiltà Roman - The Rome of today and the glory
that was Rome.

Museo della Civiltà Roman - Model of the Mons Capitolinus

Jacques Plassard's Les Maquettes - Histories and models of the
Rome Empire, circa 100 AD

Wikipedia - The free encyclopedia - i.e. "Ancient Rome"

Google - Countless subject resources - i.e. "Ancient Rome"