Panagia Portiani of Zefyria is located at the settlement’s square. It is a big and impressive church with stone domes. On the south wall, internally, relics of frescoes are preserved. The date of its construction is not known, but it was certainly before 1645. The church is dedicated to the Dormition of the Virgin Mary. On the north wall, a door leads to the smaller church of Agios Charalambos which is older than Portiani. A characteristic of the churches is that materials of volcanic origin have been used and in particular the “sugar-rock” (the local name for perlite) of Milos.