One of the main attractions of the beautiful Greek Islands of Hydra and its eponymous capital is the Cathedral known as the Church of the assumption Monastery of the Dormition, or the "monastery". The Cathedral is the main center of the Greek Orthodox Church on the island of Hydra. It is located on the promenade and it is impossible to miss (the main reference is towering high above the Harbor marble clock tower).

The first Church and some monastic cells were built in 1643. In 1774 as a result of a strong earthquake the original structure was heavily damaged and subsequently restored Venetian architects.

The katholikon of the monastery is built in Byzantine style and impresses with its magnificence. Breathtaking and the interior with its marble iconostasis, excellent frescoes, the earliest of which date from the early 18th century, ornate chandeliers, a huge number of gold and silver icons of the Byzantine period, etc.

In the monastery complex today houses various government agencies, including the city hall. In the courtyard are statues of heroes of the Greek revolution in the struggle for independence from the Ottoman Empire (of Theodoros kolokotronis Theodoros, Andreas Miaoulis, etc.) you will also see the tomb of Lazaros of Kountouriotis and war memorial, dedicated to the Balkan wars.

Special attention deserves and located in the former monastic cell is a small but very interesting Ecclesiastical Museum, founded in 1933. In the Museum you can see various religious relics, historical documents, luxurious liturgical vestments, jewelry, and much more. The Museum's collection is of great historical and cultural value.