The temple complex is on a raised plaza erected over an earlier T-shaped base consisting of a podium, staircase, and foundation walls. These walls were built from about 24
monoliths, at their lowest level weighing approximately 300 tonnes each. The tallest retaining wall, on the west, has a second course of monoliths containing the famed "
Three Stones" (,
Trílithon): cut from
limestone, measuring over long, high, and broad, they weigh approximately 800 tonnes each. (A fourth, still larger stone called the
Stone of the Pregnant Woman lies unused in the nearby quarry from the town and weighs around 1,000 tonnes. A fifth, weighing approximately 1,200 tonnes lies in the same quarry.) Through the foundation there run three enormous passages the size of railway tunnels. A wide staircase provided access to the elevated platform, which measured on top. The Temple of Jupiter proper was circled by a
peristyle of 54 unfluted
Corinthian columns: ten in front and back and nineteen along each side. The columns were 19.9 meters high, the tallest of any classical temple, and the apex of the
pediment is estimated to have been 44 meters above the floor of the court. With a rectangular footprint of 88 by 44 meters, it is considerably smaller than earlier
Greek temples, such as the
Temple of Artemis at
Ephesus and the Temple of Apollo at
Didyma. Rather its significance lies in the sophistication of its planning and architectural detail. A number of
Julio-Claudian emperors enriched the temple's sanctuary in turn. In the mid-1st century,
Nero built the tower-altar opposite the temple. In the early 2nd century,
Trajan added the temple's forecourt, with
porticos of
pink granite shipped from
Aswan at the southern end of
Egypt. The Temple-Sanctuary of Heliopolitan Zeus was ruined by earthquakes, destroyed and pillaged for stone under
Theodosius and again under
Justinian: eight columns were taken to
Constantinople (
Istanbul) for incorporation into the
Hagia Sophia. Three columns fell during the late 18th century. ==Construction==