Siracusa's Duomo is an archive of island history: the bottommost excavations have unearthed remnants of Sicily's distant past, when the Siculi inhabitants worshipped their deities here. During the 5th century BC (the same time as Agrigento's Temple of Concord was built), the Greeks erected a temple to Athena over it, and in the 7th century Siracusa's first Christian cathedral was built on top of the Greek structure. The massive columns of the original Greek temple were incorporated into the present structure and are clearly visible, embedded in the exterior wall along Via Minerva. The Greek columns were also used to dramatic advantage inside, where on one side they form chapels connected by elegant wrought-iron gates. The Baroque facade, added in the 18th century, displays a harmonious rhythm of concaves and convexes. In front, the piazza is encircled by pink and white oleanders and elegant buildings ornamented with filigree grillwork.