Panagia Ekatontapyliani or Katapoliani is the sacred jewel of Paros, one of the most important early Christian monuments of Greece.

It is located within the village of Parikia, on the east side and near the harbour, and has a remarkable and important history that begins from the Byzantine period.

The temple owes its name to its 100 gates, 99 of which are visible and the hundredth will be revealed when the Greeks will recapture the Constantinople, as it is said.
The Katapoliani, probably derived from the term "Katapola" meaning "in town", probably indicating the location of the ancient city of Paros.

Its construction, according to tradition, must be started in the 4th century by St Helena, the mother of Saint Constantine, who made a vow that if she found the Holy Cross, she would build a church at the location of a small temple she had found when she stopped in Paros throughout her journey to find the cross. Then, after she carried out the purpose of her trip, she fulfilled her promise.

In another version, the church was built by the Constantine the Great, with a mandate that received from his mother because she did not manage to fulfil her vow.

In the beginning, it had a form of a wooden-roofed in the shape of a cross basilica church, which was probably destroyed by fire. At the period of Iustinianos, it was rebuilt and shaped with domes and cupola. According to tradition, the church is the work of the student of the master builder who built Agia Sophia in Istanbul.

At the period of Frankish and Ottoman rule, it was destroyed and looted several times, while the biggest disaster came with the earthquake of 1773. Afterwards, many other repairs and modifications were made, which distorted its original majestic form.

The present shape of the temple has the form of the age of Iustinianos, domed basilica in the shape of a cross and is the work of the archaeologist Anastasios Orlandos, at the period of 1959-1966. With his research showed that there was there a holy Christian church before the 6th century, thus confirming the tradition that Ekatontapyliani was founded by the Apostles.

The temple is decorated with sculptures from the ancient temple of Demeter, which was at the port of Parikia.
In the southern part of the church is the baptistery of the fourth century, the oldest and best preserved baptistery throughout the whole Orthodox East with the oldest mural that has ever found on the island, which is of the 11th - 12th century, and depicts the St. George.

Ekatontapyliani is a large complex consisting of the main temple and other buildings, like the six chapels that are dedicated to Saints, the Chapel of St. Nicholas, of Saints Anargyroi, St. Philip, St. Theodosia, St. Demetrios and Osia Theoctisti and the complex of cells of the 17th and 18th centuries.
The whole complex has the look of a monastery and is surrounded by a majestic white fence of 8.5 meters and 252 meters in perimeter, which has a protective purpose.

One of the cells houses the Byzantine museum of ParIkia of fine art images, woodcuts and other sacred relics from the period of Byzantine and Ottoman rule.