Standing at the crossroads of East and West, Istanbul represents so many stories and cultures. There are equally many different moods and facets, making it difficult to know where to begin her story. In my case, I decided to start with the Byzantine monuments of Istanbul, better known as Constantinople by that time. For over 1000 years, it was one of the world’s most desirable cities, adorned with huge palaces and magnificent churches.

Even though most churches are now converted to mosques and other structures have largely been left in ruin, the footprints of the Byzantine Empire are still visible within the city. In fact, without the Byzantines and their urban transformation from a sleepy trading post to an imperial capital, Istanbul today would probably never have existed. The city not only built itself by incorporating the former empire’s territories and populations but has also adopted a variety of cultural and religious influences.

Constantinople was founded in 330 by Constantine, the first Roman emperor to convert to Christianity. He wanted to build a splendid new capital to replace Rome which by the time was too far from the Danube and Euphrates frontiers. A Greek trading port called Byzantium on the banks of the Bosphorus Strait was chosen to be the site for this monumental project. Within six years, an extensive building campaign was carried out, completely transforming the cityscape.

After Ravenna – the seat of the Western Roman Empire government – fell into the hands of barbarians in 476, Constantinople became the sole capital of the Roman Empire. The city accepted scores of refugees from the western territories and was the pinnacle of civilization during Europe’s Dark Age. Constantinople enjoyed steady growth for several centuries despite some setbacks until European Crusaders breached its defensive walls in the 1200s. The city was ravaged, with nearly all its physical riches spirited away to Europe. While the Byzantines eventually regained control of the town, its glory faded forever. In 1453, Sultan Mehmed II of the Ottoman Empire dealt the final blow. The city fell after a 53-day siege, marking the end of Constantinople as the capital of the once-powerful Roman Empire.

From the mid-5th century to the early 13th century, Constantinople was the largest and most important urban center in the Mediterranean. It dominated much of the economic life in the region, as a result of its commanding position on sensitive routes between Anatolia and Balkan, as well as between the Aegean Sea and the Black Sea. The city was also a center of ancient Greek and Roman culture and became famous worldwide for its architectural masterpieces.

Known as Basileuousa (Queen of Cities), Constantinople was Europe’s largest and richest city.

There is no better way to demonstrate the skill and caliber of Byzantine architects than Istanbul’s Hagia Sophia. Meaning “Holy Wisdom”, this magnificent structure was originally the center of the Eastern Orthodox Church. It was constructed in the aftermath of the Nika Revolt, which destroyed many of the city’s monuments. Emperor Justinian commissioned this church in 532 to improve his tainted image at home. Hagia Sophia was the third building to be erected on this site. However, its architecture far surpassed its predecessors.

Hagia Sophia is the pinnacle of Byzantine architecture.

Being the largest cathedral ever built up to that time, Hagia Sophia is considered the pinnacle of Byzantine architecture. Its sheer beauty, with monolithic marble columns, refined lattice, stucco, and gold mosaics, is enough to make any worshipper burst into tears of joy. However, the most spectacular part is the central dome, measuring 32.6 meters in diameter. Without any supporting column, the dome looks as though it’s hanging from heaven. The effect is even accentuated by 40 arched windows around the dome base They let light reflect into the nave and seemingly separate the main structure from the dome.

After being converted into a mosque in 1453, several Islamic elements were added to Hagia Sophia. For example, the four limestone minarets and the golden crescent atop the dome. Inside, eight medallions with Arabic calligraphy were hung on the four piers, both sides of the apse, and the west doors. Figurative decorations were, however, covered by plaster. By the late 16th century, Hagia Sophia received structural stabilization for the first time, allowing it to withstand many earthquakes. Interestingly, this new appearance of Hagia Sophia later became the prototype for many other mosques across the Ottoman Empire. And to this day, this unique religious monument continues to dominate the Istanbul skyline.

Just a few steps from Hagia Sophia is another Byzantine church, Hagia Irene, or “Sacred Peace”. It was the third structure standing on this spot after the first two churches – commissioned by Emperor Constantine in the 4th century and Emperor Justinian in the 6th century – had been destroyed. Compared to its predecessors, Hagia Irene of the 8th century looks far more humble as it was built during a period in which most religious images and icons were banned.

Decorations are, therefore, limited to simple carvings, and the dome above the apse features nothing but a plain cross. Ironically, due to this absence of human figures, Hagia Irene is the only Byzantine church in Istanbul that was never converted into a mosque. Instead, it was used by the Ottomans as an armory. Throughout its history, Hagia Irene witnessed the rise and fall of both the Byzantines and the Ottomans. These days, the building operates as a museum and occasionally as a concert hall.

Right in front of Hagia Sophia used to be the site of Hippodrome – a massive stadium for horse racing with a capacity of up to 40,000 spectators. It was the center of Constantinopolitan social life as horse racing was a popular pastime during the Byzantine period. In the aftermath of the Fourth Crusade, the stadium was in ruin, with many of its decorations looted and transported to Europe. The Hippodrome became a public square under Ottoman rule and it continues to play that role to this day as Sultanahmet Square.

Though the stadium is no longer evident, significant traces of it can still be seen in today’s Istanbul. For instance, a 3500-year-old granite obelisk from Luxor, a serpent-shaped column from Delphi, and an ancient masonry obelisk. These valuable monuments were set up in the middle of the Hippodrome and served as the central barrier of the racetrack. They were brought here from across the empire, to showcase the wealth and power of the Byzantine rulers.

Apart from the nearly impregnable fortifications, the reason why Constantinople could repel numerous invasions was the system of cisterns lying beneath the city. Tens or even hundreds of such subterranean reservoirs were cautiously dug throughout the ages. They ensured that the city could stay under siege for months. And the largest and most impressive among them is the Basilica Cistern.

Constructed under the reign of Emperor Justinian to supply water for the imperial palace, Basilica Cistern could store up to 80,000 tons of water. It was named as such because a basilica once stood above this spot. 336 marble columns, each measuring nine meters in height, are used to support this grand brick vault. Some have Corinthian capitals, while others stand out without any decoration. Curiously, there are columns that seem to be brought from where else, such as the two with reversed Medusa heads and the so-called “tear column”.

With the conquest of Constantinople, Basilica Cistern nearly fell into oblivion. It was only rediscovered by chance in 1545 when French scholar Petru Gyllius studied Byzantine antiques in the city. Even so, the Ottomans loathed stationary water and treated the “Subterranean Palace” like a dumping ground. The cistern underwent cleaning and restorations in the mid-1980s. And since then, it has become one of the most intriguing cultural assets in Istanbul.

Basilica Cistern could store up to 80,000 tons of water.

Another landmark that’s hard to miss in Istanbul is the Galata Tower. Strategically located atop a hill overlooking the Golden Horn and the Bosphorus, this cylindrical structure served as a fire watchtower of Constantinople. Its exterior was largely made of rough-shaped rubble masonry, while bricks were the main components of the interior. In addition to the surveillance function, Galata Tower played a crucial role in defense. It marked the northern end of a gigantic chain, which stretched across the mouth of the Golden Horn to block enemy ships.

Despite being erected during the Byzantine period (1348-1349), this iconic tower was not the work of Constantinopolitans. Instead, the Genoese built this tower as part of a fortification to protect their colony on the northern bank of the Golden Horn. However, it was the second tower to occupy this site. The first one commissioned by Emperor Justinian in the 6th century collapsed during the Fourth Crusade. Under Ottoman rule, Galata Tower continued to be used as a fire watchtower, and prison for a time, before being converted into a museum in the 1960s.