North of the ancient city of Alauna, now covered by pastures and hedgerows of the Norman bocage in the 21st century, the baths are situated near a road considered the cardo maximus.

[3] The thermal complex is situated at the eastern end of Rue du Balnéaire, outside the main built-up area of Alleaume and to the southeast of the settlement.

[A 1] The depression through which the Merderet River flows is partially filled with Hettangian deposits (Early Jurassic) as a result of a marine transgression that encroached upon the western edge of the Paris Basin.

Local geological materials such as red clays, sands, gravel, and Rhaetian pebbles (Late Triassic) from the plateau, as well as Jurassic limestone from the slopes, are utilized in the construction of buildings in Alauna, including the baths.

[AG 2][F 1] The construction of the baths in Alauna likely took place in the second half of the 1st century, around 60 to 80 AD, during the city's development and expansion phase when its main monuments were being built.

Latrines were added against the western wall near the water inlet, and an external pool may have been attached to the same room, but the exact dates of these additions are unknown.

This phase of "differentiated reuse" explains the distribution of the preserved remains in elevation in modern times, protected from destruction by their inclusion in other buildings that were later destroyed.

[PN 1][12] In 1688, Louis Le Vavasseur de Masseville reported the tradition of an ancient city at the site of Alleaume, mentioning the "old castle of Vallongnes,"[13] sometimes attributed to Clovis.

[17][N 2] In the seventh volume of his Collection of Egyptian, Etruscan, Greek, Roman, and Gallic Antiquities, Anne Claude de Caylus published accurate drawings and partial plans of the baths in 1765, created by the engineer René Cevet.

[A 4] The Normandy Antiquarian Society continued Gerville's work at Alleaume in 1845 but was unable to access the baths due to the landowner's restrictions.

Between 1989 and 1992, at the request of the municipality of Valognes to prepare for the site's enhancement, the baths underwent complete excavation, their layout was finalized, and their timeline was clarified.

[28] It serves as the starting point for guided tours organized by the Agglomération antique d'Alauna (Ancient Agglomeration of Alauna Association or AAA) in partnership with the Clos du Cotentin Art and History Region, especially during the European Heritage Days.

[PN 3] The width of the outer walls of the thermal complex is also determined by this principle, measuring 1.20 m, equivalent to 4 Roman feet, or one-thirtieth of an actus.

[PN 4] The decision to replicate specific rooms likely serves the purpose of adjusting the bath's capacity based on usage rather than segregating men and women, who will ultimately convene at the pools and sudatorium, shared spaces.

This design choice eliminates the need for extensive excavations to create the 1.25 m high service basement required for the proper functioning of these rooms (ovens and hypocausts for underfloor heating).

[PN 3] In the lower parts of the sudatorium, CBM is used alone due to its refractory qualities, in contact with the praefurnia and forming the mass of the hot pool.

[F 5] The absence of CBM in alternating layers with the rubble in the facing of the walls (opus mixtum) suggests the baths were constructed before the 2nd century, a time when this architectural feature was becoming more common.

[PN 4] The outer walls do not appear to have been coated with plaster, relying on the alternation of stones and bricks for decoration, along with protrusions and recesses creating depth and shadow effects.

The interior decoration of the rooms, likely richer with painted plaster or veneers as is often the case,[35] remains unknown, with any usable traces having disappeared,[AG 6] except for limestone slabs covering the floor and walls of the cold pool.

Historical excavations reveal that the spring supplies water to the baths through a system of artificial regulation and a retention pond,[37] followed by an 800-meter-long aqueduct with a 19-meter drop.

[AG 4] In the northern part of the settlement, an area served by the Alauna roads but sparsely built, a ground-penetrating radar survey in 2020 revealed "anomalies" that could correspond to channels, tubular or covered trench pipelines, as well as tanks or reservoirs.

This structure seems to consist of a courtyard surrounded by a peristyle, possibly the palaestra, a feature commonly found near baths but not previously identified in Alauna.

Situated between the baths and the cardo maximus, a partitioned building may be associated with the thermal complex, housing rooms with various functions such as a gymnasium.