In its heyday, Delos was a political, cultural and economic hub of the Hellenic empire. Today, it’s an experiential outdoor antiquities museum, featuring the long-gone civilization through unearthed mosaics, jagged pillars and chipped phallic statues. And about 15 minutes by foot from what might be considered Downtown Delos, past an unattractive building with displays of busts and busted artifacts, beyond the staff huts, and nearly on the beach lies the Delos Synagogue, basically the outline of a two-room stone structure dating to the second century BCE.This is just a taste of a long article, worth reading in full. I can't find any past PaleoJudaica posts on the Delos "synagogue," but this post gives some background on that "Holy Argarizein" inscription and its connection to Samaritan Mount Gerizim.
It is known as a synagogue primarily because the museum’s map says it is, and because there is a stone plaque at its entrance with the word “synagogue” chiseled in both English and Greek. Archaeologists proclaimed it such a century ago, but some scholars disagree whether it was in fact a Jewish place of worship, or a Jewish place at all.
[...]
First fruits for Holy Argarizein
The inscriptions found on or near GD 80 are not biblical prayers scrawled in Hebrew or Aramaic. That would be too easy. Rather, they reference names that Plassart identified as Jewish (Agathokles and Lysimachos) and contain the word proseuche, which can refer specifically to a Jewish house of prayer - or can be applied more generally as a kind of offering.
If anything, additional inscriptions uncovered in 1979 actually offer explicit evidence of a Samaritan presence. Two of them honor benefactors of the community and begin: “The Israelites on Delos who make first-fruit offerings to Holy Argarizein” – which is a reference to Mount Gerizin, in present day Nablus, which is part of ancient Samaria.
[Historian Lidia] Matassa is unconvinced that this answers the synagogue question one way or another. She points out that there is no way to know whether the dedications where made by a permanent community, or by a passing traveler.
The physical structure of the space offers few clues, since it largely echoes the architecture and design of neighboring buildings. It is, however, found on the eastern shore and has a clear eastern orientation, which is characteristic of many synagogues.
As for the alleged mikveh, Matassa and others claim it is a mere cistern, which, at the time of use, would have been subterranean and impossible for a person to use.
UPDATE (25 October): An alert reader has sent in some helpful links. First, this article by Lidia Matassa: Unravelling the Myth of the Synagogue on Delos (Bulletin of the Anglo-Israel Archaeological Society 2007 Volume 25, pp. 81-115). Second, I noted a review of Anne Katrine de Hemmer Gudme, Before the God in this Place for Good Remembrance. A Comparative Analysis of the Aramaic Votive Inscriptions from Mount Gerizim here last year. And third, this article by Monika Trümper: The Oldest Original Synagogue Building in the Diaspora: The Delos Synagogue Reconsidered (Hesperia: The Journal of the American School of Classical Studies at Athens
Vol. 73, No. 4 (Oct. - Dec., 2004), pp. 513-598). The latter is available at JSTOR with a free registration.