Thelpusa — also written Thelpousa, Telphusa, or Telphousa — took its name, ancient sources said, from a nymph who was the daughter of the river Ladon itself. The nymph's name was probably that of the stream flowing through the lower part of the town into the Ladon, the city's naming its own identity from the water that defined it. The city sat upon the left, or eastern, bank of the Ladon, with its territory bounded by Psophis to the north, Heraea to the south, Eleia and Tisatis to the west, and Cleitor, Tripolis, and Theisoa to the east. Its geography was typical of northern Arcadia: river valleys, forested ridges, territories defined by the watersheds between them.

Thelpusa makes its first historical appearance in 352 BCE, when Lacedaemonian forces were defeated in its neighborhood by the Thebans — a reminder that even small Arcadian cities found themselves swept into the great military contests of the classical Greek world. In 222 BCE, Antigonus Doson took the city during his campaign against Cleomenes III of Sparta. Philip V of Macedon also figures in its story. Its coins confirm it belonged to the Achaean League, giving it regional standing even as Arcadia's great age of independence faded.

When Pausanias visited Thelpusa in the second century CE, he found the city nearly deserted. The agora, once at the city's center, had drifted to its edge as the population contracted. He noted a temple of Asclepius and another to the twelve Olympian gods, the latter nearly leveled. But the two temples in the city's neighborhood drew his particular attention.

Above the city stood a temple of Demeter Eleusinia, containing stone statues of Demeter, Persephone, and Dionysus — the conventional, life-giving aspect of the goddess. Below the city, at Onceium, stood the other: the temple where the Thelpusians called Demeter by the name Erinys, meaning Fury. The myth behind this name was specific and violent. According to the tradition preserved here, after Poseidon had attacked Demeter in the form of a horse, the goddess wandered in grief and rage, her horse's head a mark of her transformation, before she was eventually calmed. The Thelpusians preserved this darker mythological memory when other communities had moved on to the more palatable Eleusinian version. Near the Erinys temple stood a temple of Apollo Oncaeates, and across the Ladon, a temple of Asclepius — together forming a dense sacred landscape along the riverbank.

Lycophron and Callimachus, both prominent Hellenistic poets, allude to this temple, suggesting it was well known enough to merit literary reference beyond its local setting.

By the nineteenth century, when European antiquarians and travelers began systematically documenting Greek ruins, Thelpusa was a ghost. The city's remnants were found on the slope of a considerable hill near the village of Vánena (also spelled Vanaina), north of Toubitsi. Visitors described only sparse traces of the city walls. At a ruined church of St. John, near a rivulet, excavators found Hellenic foundations and fragments of columns — the saint occupying the site of what Pausanias had described as the temple of Asclepius, which he noted stood longest of all the city's structures. The pattern of Christian churches succeeding pagan healing sanctuaries is common across Greece; here, the continuity was explicit.

A Roman-era building, roughly twelve yards long and six wide, with the ruins of an arched roof, survived alongside six column bases near the Ladon itself. The soldier-antiquary William Martin Leake, whose systematic surveys of Greece in the early nineteenth century provided foundational data for classical topography, found additional column remains at the ruined church of St. Athanasius the Miraculous on the Ladon's right bank.

Pausanias, traveling the road from Psophis southward, counted 25 stadia to the ruins of the village Caus and a roadside temple of Asclepius Causius, then another 40 stadia to Thelpusa itself — a day's walk in the mountains of Arcadia.

Thelpusa is not a site with a visitor center or excavation trenches. The land near Vánena holds quiet fields and hillsides, and the ruins are low and scattered — foundation stones, column drums, sections of wall — the kind of remnants that reward careful looking but do not announce themselves. The Ladon still runs below, green and cold, descending from its springs in Cleitorian territory through the western Arcadian valleys toward the sea.

What distinguishes Thelpusa in the record of Greek religion is precisely what cannot be seen: the theological specificity of its cult. The city held onto the horse-headed, furious aspect of Demeter when the rest of the Greek world had softened her into the Eleusinian mystery goddess. That choice — or perhaps that inheritance — made Thelpusa a place where an older, darker layer of Greek religious thought persisted. The Ladon carried many stories along its length. At Thelpusa, it ran beside the temple of a goddess who had not forgiven what was done to her.