Dec. 27, 537: Istanbul’s iconic Hagia Sophia cathedral is completed

(Photo by Carsten Koall/Getty Images)

Hagia Sophia has long been a place of pilgrimage, and it still is for millions of visitors to Istanbul, Turkey. One of the most remarkable things about this domed structure with towering minarets is its age: the main part of the current structure was finished in 537.

It wasn’t even the first church on the site. Two previous basilicas had been built there, both destroyed during riots, when Emperor Justinian I decided to build a much larger and more elaborate center of worship for the Eastern Orthodox Church. For almost a thousand years, the Byzantine building (whose name comes from the Greek words for “Holy Wisdom”) was the world’s largest cathedral.

Appropriately for a building sitting at the confluence of eastern and western cultures, Hagia Sophia drew on both Greek and Egyptian architectural styles. A mathematician and a physicist designed its massive dome, which rests atop multiple marble-clad pillars and is surrounded by smaller half domes atop repeating arched windows. The design would influence Byzantine and other architecture around Europe and the Middle East. Its shape changed over the centuries: Earthquakes repeatedly damaged the structure, resulting in waves of reinforcements. Decorations have been added and removed according to religious dictates of the times.

Originally full of Christian relics and frescoes, the building’s interior was significantly modified when Ottoman Turks took over in 1453, looting the interior and turning the building into a mosque. The Ottomans also added minarets surrounding the central dome. The last major renovations were in the 1800s (with additional restoration in recent years). In 1935, Mustafa Kemal Atatürk, founder of the Republic of Turkey, declared that Hagia Sophia would become a museum. Now, visitors can wander through and marvel at centuries of history encapsulated in one magnificent edifice.