Remains of the Tarpeian Rock in Rome, June 2012

The Tarpeian Rock (Latin, Rupes Tarpeia or Saxum Tarpeium) was a steep cliff of the southern summit of the Capitoline Hill, overlooking the Roman Forum in Ancient Rome. It was used during the Roman Republic as an execution site. Murderers, traitors, perjurors, and larcenous slaves, if convicted by the quaestores parricidii, were flung from the cliff to their deaths. Those who had a mental or significant physical disability also suffered the same fate as they were thought to have been cursed by the gods.

According to early Roman histories, when the Sabine ruler Titus Tatius attacked Rome after the Rape of the Sabines (8th century BC), the Vestal Virgin Tarpeia, daughter of Spurius Tarpeius, governor of the citadel on the Capitoline Hill, betrayed the Romans by opening the city gates for the Sabines in return for 'what they bore on their arms.' She believed that she would receive their golden bracelets. Instead, the Sabines crushed her to death with their shields, and her body was buried in the rock that now bears her name.

About 500 BC, Lucius Tarquinius Superbus, the seventh legendary king of Rome, leveled the top of the rock, removing the shrines built by the Sabines, and built the Temple of Jupiter Capitolinus on the intermontium — the area between the two summits of the hill. The rock itself survived this remodelling, being used for executions well into Sulla's time (early 1st century BC).

Note the Latin phrase, Arx tarpeia Capitoli proxima ("The Tarpeian Rock is close to the Capitol"): one's fall from grace can come swiftly.

To be hurled off the Tarpeian Rock was, in some sense, a fate worse than death, because it carried with it a stigma of shame. The standard method of execution in ancient Rome was by strangulation in the Tullianum. Rather, the rock was reserved for the most notorious traitors, and as a place of unofficial, extra-legal executions (for example, the near-execution of then-Senator Gaius Marcius Coriolanus by a mob whipped into frenzy by a tribune of the plebs).

Text from: en.wikipedia.org/wiki/Tarpeian_Rock