Albunea, also known as the Tiburtine Sibyl, is the Goddess of the sulphur springs at Albulae Aqua, not far from the modern town of Tivoli, known in ancient times as Tibur. Like many Goddesses or Nymphs connected with springs, She was believed to be a healer and prophetess, since spring waters well up from the earth and represent communication between the surface (the land of mortals) and the underworld (the land of the dead and/or the Gods). Her worship is very ancient and likely goes back to Etruscan times. The waters of Albunae Aqua are a strange (and smelly) bluish-greenish-white due to the high mineral content (mostly sulphur and lime), hence the name, which means "White Water". The water that forms the small lake of Albulae Aqua, (the modern Lago della Regina, "Lake of the Queen") formerly emptied into the Anio River, which in turn joined the Tiber, the river that flows through Rome. In modern times most of its waters are diverted to the modern spa, not far from where the ancient baths were. The Tiber itself was also known in ancient times as the Albula—which is unusually enough a feminine name when most river-names were masculine—though there is disagreement as to whether it got its name from Latin albus, "white", which would refer to the white sulphur-laden waters from the Anio, or from a Ligurian root alb- or alp- meaning "mountain"—i.e., "the stream from the mountains". Albunea is connected with both the river and the springs, and whatever the actual derivation of Her name was, She is known as "the White Sibyl". Albus has the additional meaning of "favorable" or "auspicious", certainly appropriate to describe one who foretells the future.

Albulae Aqua's sulphurous waters have long been famed for their reputed healing properties and ability to cure diseases, and in ancient times were believed especially helpful in mending broken bones. The local travertine marble is white, and in both ancient and modern times was quarried for buildings; since limestone dissolves in acidic water, only to later precipitate out and form layers of stone (stalactites and stalagmites in a cave are examples of this process), perhaps the slow build-up of white stone around the springs was equated with the repair of bones. The waters were both used for bathing (they come from the ground at a tepid 75 degrees Fahrenheit) and drinking as a tonic, and in modern times the fumes are breathed in as a cure for lung problems.

In classical times, the lake was said to have been home to several floating islands—low round islets covered with grass that moved freely about on the surface. They no longer exist (perhaps because the chemistry has changed slightly due to the water being diverted); but the cenote (water-filled sinkhole) of Zacaton in Mexico has a number of similar islets—no one is quite sure how they form, but it it believed to have something to do with the chemicals in the water that allow certain substances (such as travertine marble) to float when they normally would not. Pliny (the Younger) has an account of this type of island on a similar lake in Italy. He tells of how they would float about on the surface, moving where the breezes took them, sometimes scattering them, sometimes gathering them against the shore. Once in a while an innocent local sheep would wander onto one of the islands without realizing it, being far too occupied with the serious business of eating to look up. It would continue blithely munching, unaware that the island was slowly creeping away. By the time the sheep noticed, it was usually all alone in the middle of the lake, and would freak out (I paraphrase). Pliny goes on to say—and he must have been a kindhearted soul—that the wind would eventually bring the sheep back to the shore where it could step off, none the worse for wear.

Albunea had a sacred grove not far from Her springs, and a temple in Tivoli, though which one it is of the temples that remains is debated. Tivoli (or Tibur) is not far from Rome and has been famous as a resort since ancient times: there two temples stand on a high hill overlooking the gorge of the river Anio (the modern Aniene River) and its gorgeous waterfalls. Though next to each other, and perhaps linked in cult, the temples are stylistically quite different: one is round, much like the Temple of Vesta in the Forum in Rome, and the other is of the more usual rectangular plan. Both of these have at times been said to be the Sibyl's; though it is more likely that the rectangular one was Hers. Albunea's grove and springs later hosted a shrine of Faunus, who was similarly regarded as a prophetic deity, and there He gave His oracles through the method of incubation, the practice of sleeping in a temple or holy place to receive a meaningful dream. Perhaps this practice of divination through dreams was inherited from Albunea, for it had been Her place since very ancient times.

There were known to be nine famous sibyls or prophetesses in the ancient world, from Delphi in Greece to Cumae in Italy, to Libya in Africa to the Hellespont in Asia Minor. There were all women, old or young, said to have prophetic powers. To these nine the Romans added their Albunea, calling Her the Tiburtine Sibyl after the town where Her worship was centered. She was said to have written certain books of prophecies, which were stored in Rome with the more famous Sibylline Books, which had been sold to the legendary King Tarquin by the Cumaean Sibyl, and which were consulted by the Senate in times of trouble. Albunea's statue was said to have been found in the bed of the Anio, and showed Her as a Nymph holding a book.

Albunea was associated with Mefitis (a Goddess of noxious swamps) and the Greek Leucothea (whose name means "the White Goddess"), a name of Semele, the reborn mother of Dionysos.