Allianoi is an ancient spa settlement, with remains dating predominantly from the Roman Empire period (2nd century AD) located near the city of Bergama (ancient Pergamon) in Turkey's İzmir Province. The site is at a distance of 18 kilometers to the northeast of Bergama, on the road to the neighboring town of İvrindi. Allianoi is directly inside the reservoir of the Yortanlı Dam, built by the Turkish State Hydraulic Works. After ongoing discussion in Turkey with regards to preserving Allianoi's ruins, the site was covered with sand and the dam was activated, resulting in Allianoi's complete inundation and destruction in February 2011.^{[citation needed]}

One particularity of Allianoi is its being a very recent historical discovery. It was mentioned only once in the 2nd century by the orator and medicinal writer Aelius Aristides in his "Hieroi Logoi" (Sacred Tales) (III.1), one of the key sources for the knowledge on the science of healing as it was understood at that time. No other writer of antiquity nor any epigraphic finding known had referred to Allianoi.