Iera Moni Koimiseos Theotokou Krustallenias

It is not known when the monastery was founded. Vasilios Psilakis reported that revolutionaries gathered at the monastery in 1272 to pray before the Lasithi plateau became a base for the revolution. Nikos Psilakis reports that this information suggests that the monastery existed from the second Byzantine period. The old agiothyridos of the monastery is dated 1241. However, the Venetians, in the context of suppressing the revolutions, prohibited access to the plateau from 1293 to 1543, with severe penalties for offenders, even death. 

With the repopulation of the plateau in the 16th century, the nuns Palantia and Theoklite arrived from the Peloponnese. The nun Palantia, from the monastery of Panagia Spilaio, founded the monastery of Kroustallenia, while the nun Theoklite founded the monastery of Agia Pelagia, of which only the church now survives. After the conquest of Crete by the Ottomans , male monks settled in the monastery.  During the Ottoman period, the monastery became a meeting place for the captains of the region. It was also a place of hospitality for foreigners, such as the traveler Siber in 1817.