A modern term for the sacrificial area of any Phoenician/Punic settlement. These were the sites of the infamous infant sacrifice that seems to have been the central rite of Phoenician religion1.
The most famous is the tophet at Carthage, which provides the best physical evidence for the practice. It was "discovered" in 1921 when a French officer interested in antiquities followed his dealer to the source.
The tophet was once an open area scattered with small stone markers. It seems to have been the site of the actual sacrifices as well as the place of internment for remains2. Excavations revealed that it covered about a hectare at its greatest extent and had been in continuous use from about the 8th century to the 2nd BCE (probably right down to the destruction of the city by Rome in 146 BCE, and perhaps beyond).
Individual finds consisted of a small ceramic urn containing the cremated remains of an infant, child or animal. This was covered with a flat stone, and on top of that there was sometimes placed a cippus with a formulaic inscription (compare the Roman ex voto) dedicating the remains to the goddess Tanit and to Baal Hammon3. The total number of sacrifices made throughout the city's history seems to have been in the tens of thousands4.
Studies of the remains at different layers revealed some unexpected trends in the development of the sacrificial rites. The earliest urns contained very young infants (possibly even stillborn babies), with animals substituted about a third of the time. In the upper (later) levels, the remains are of children between one and three, and the proportion of animals falls to about one in ten. The rite thus seems to have become stricter and more cruel as time went on, despite contact with other civilizations that had moved decisively away from human sacrifice.
With the destruction of Carthage itself at the end of the third Punic war, the tophet was finally put out of use. Tertullian, however, claimed that the practice persisted in the region as late as the third century CE5.
1 To be fair, there is still some debate over the possibility that the infants and children died of natural causes and that the areas are simply special cemetaries; but this is regarded as (and seems) pretty unlikely.
2 As far as I know, nothing reliable is known about the actual rite. There are some suggested reconstructions in Lancel, especially on p.254 and 255, but one's sensational and the other boring.
3 Baal Hammon was eventually syncretized with the Greek Kronos and the Roman Saturn, Tanit with Juno/Hera. This doesn't mean, of course, that they were much alike to begin with.
4 Lancel, p.250: "An American team estimated the number of urns that the tophet may have received between 400 and 200 BC at around 20,000".
5 It's difficult to say how likely this really is. As a Christian, Tertullian may have just been repeating well-worn slanders about the pagans. Similar stories of baby murder are known to have circulated about the early Christians, as they did about Jews in Europe into the 20th century.
Serge Lancel, Carthage: A History
A History of Rome, M.Cary and H.H. Scullard
The Oxford Classical Dictionary, Third Edition (ed. Simon Hornblower and Anthony Spawforth)
Classical and biblical references to Phoenician infant sacrifice:
Plutarch, De superstitione, 13
Diodorus Siculus XX, 14, 4-7
Tertullian, Apology 9:2-4
II Kings 17:17
(but see also Genesis 22:1-17 and, especially, Judges 11:30-40)