Located in Blachernae (Region XIV).

According to Cedrenus (12th century) built in the late 6th century by Tiberius II and Maurice (mistakingly attributed to Leo I in Pseudo-Codinus/Patria), located in the "Carian portico" (exact location unknown). Pseudo-Codinus/Patria claims Basil II restored it (Janin, 1964, p. 218). Yegül, 2008, p. 183 claims it belonged to the Blachernai Palace complex, including the Theotokos Church.

Pseudo-Codinus/Patria also tells us of a "sacred bath" (hagion loutron) in Blachernai. Synonymous with the public bath? Or perhaps the hagiasma of Theotokos Blachernai?

Yegül, 2008, p. 191-192 writes that the baths at the Blachernai complex were part of a weekly quasi-religious ritual on Fridays where the emperor visited the bath to purify himself: first, he would arrive at Blachernai harbour, then he would attend a ceremony at the basilica, afterwards he would put on a ceremonial bathing costume at the Triconchos (between the church and bath) to pray and proceed to the bath. After dressing, a reception was held, and the emperor immersed himself in the sacred pool three times.

Location implies that Blachernai was supplied by the Hadrian Waterway.

See further Bayülgen & Saner, 2024, p. 363-365 (substructures at Blachernai, look for possible identification?)

The confusion of the "holy bath" (hagion louma) could be explained by the authors mixing up the public bath with the spring in Theotokos Blachernai (which also includes Leo I in its history). Or, as the ritual implies, the emperor made use of both.