On the four large Cycladic islands there are monasteries that wrote and continue to write history. So on the pages of this scientific, in perception and popular in writing guide: a. The active monasteries of the four islands are thoroughly presented, that is, the monasteries that maintain a small or larger monastic community today. b. Monasteries are briefly presented which remain inactive, but (renovated or not) are visitable monuments of "religious tradition", examples of architectural ingenuity, therefore highly important creations of popular tradition, with their self-evident contribution to modern Greek culture. c. Monasteries that do not exist today as such are presented by name, since, for the most part, most of today's impressive churches of Naxos and Paros were once their katholikonos, that is, their temples. [...]