A mikvah (also spelled miqvah or mikveh) is a ritual Jewish bath, used for the purpose of purification. 

When the Jews were expelled in 1492 from all of the dominions of the king of Spain and Aragon (to which Syracuse belonged, together with all of southern Italy), the Jewish community of Syracuse, in the hope of returning one day to their homeland, tried to hide the entrance to their mikvah by completely blocking and camouflaging it.

For half a millennium the existence of this space was forgotten. The conversion of to the existing building above the mikvah into a hotel, however, revealed its long access stairway, and the earth (five truckloads!) covering it was removed. The discoverers found the space perfectly preserved yet full of fresh water up to the ceiling.

The Mikvah of Syracuse appears today to visitors as a rectangular principal room, entirely excavated in the limestone rock (to a depth of 18 meters / 59 feet). Its ceiling is supported by four pillars, and the floor is punctuated with three dug baths. Its walls contain three side niches, two of which also feature a bath. One of the side niches intersected a circular well, probably from the Hellenistic period.  

An opening in the ceiling provides ventilation and illumination, which runs to the surface next to the current access to the stairs.  In the past, the small amount of light provided by this shaft was the only illumination available, save for the addition of oil lamps. Examples of these lamps were found during the excavation and are now displayed in a case in the hotel above.

According to the most recent scholarship, this space may be the most ancient ritual Jewish bath left to us in Europe: the period of construction suggested by scholars is, in fact, the 6th century A.D., in the peak years of the Byzantine period.  

For what reasons did the Jewish community of Syracuse take it upon itself to conduct this impressive work?  For religious reasons. The water of the mikvah had to be "living water," that is to say it can ebb and flow without human intervention. The constant subterranean filtration of that depth guaranteed such a characteristic, even in the middle of an island. This was the reason why the this space required such deep excavation into the subsoil: the stagnant water at surface level was not appropriate for ritual use, so the search for an appropriate water source moved deep underground.

Still today, with the out-flowing canal being obstructed by work conducted in modern times, the owner of the hotel has to regularly operate the pumps (obviously not during tours). If this is not done, the water that continuously filters through the walls of the tubs will again fill them.

The Mikvah of Syracuse is found on Via Alagona 52 (at the entrance to the “Residenza della Giudecca”), that is to say a few hundred meters from the Hotel Algilà and from the Hotel Roma. For this reason, one is advised to reach it on foot, following the streets that were once part of the Giudecca (Jewish Quarter).

Accessibility.
The descent to the mikvah is possible only using the original ancient stairs, which are very deep and rather steep. The visit is therefore not possible for those with mobility problems. The visit is also not recommended for people who suffer from claustrophobia, owing to the absence of an external opening.