Istanbul was formally known as Constantinople until the Byzantine Empire was defeated by the Ottoman Turks. Constantinople had been the center of Christiandom. The city had defended its boarders since ancient times with high walls and ramparts. The Ottomans were able to defeat it with the aid of cannons and onslaught from sea and land. After the fall of Constantinople, the city was renamed Istabul and has maintained the name to this day. 


Latitude: 41.008237600000
Longitude: 28.978358900000

Timeline of Events Associated with Istanbul

Date Event Manage

Leonardo da Vinci's Letter to Sultan Beyazid II

29 May 1453

The Fall of Constantinople

The fall of Constantinople marked the end of the Byzantine Empire after ten centuries of war. The Ottoman Turks defeated felled the city and ended the European Middle Ages. 

The Byzantine Empire had been a bastion of Christian Europe facing Muslim Asia. The Ottoman Turks were expanding their empire and saw Constantinople as a center of the rival Christian faith and a symbol of imperial power. 

Constantinople had held off many attempts to destroy or capture it but was declining in power over the years. Mehmed II set out to take the city in the spring of 1453 and used the sea to gain access to the city. Initial attacks failed, but on May 29th, Mehmed launched attacks from the sea and the land simultaneously.  The Ottomans were finally able to overwhelm the defenses due to the use of gunpowder-powered cannons. After gaining access past the walls, the Ottomans killed the emperor and massacred the citizens. 

Mehmed rode a white horse down streets that ran with blood to Hagia Sophia, the city's famed cathedral. He used the cathedral as a mosque to say prayers of thanks for the victory. 

The fall of Constantinople was important because it was a watershed moment in military history. The city had defended itself with walls and ramparts since ancient times. These fortifications were used as the model of many later cities. The end of the Byzantine Empire marks the end of the Medieval period.  

Bunting, Tony. “Fall of Constantinople.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 22 May 2018,

“Fall of Constantinople.” Wikipedia, Wikimedia Foundation, 2 May 2019,

circa. 1502

Leonardo da Vinci Designs Arched Bridge

Leonardo da Vinci was a proficient engineer as well as artist, and among his designs was a bridge entirely supported by the parabolic arch underneath it. His notebook includes two illustrations of this arched bridge. He specified that the bridge, which would span the Golden Horn connecting Galata to Istanbul, would be 600 braccia long, which is equivalent to 366 m or 1200 ft; 400 braccia spanned the inlet itself, with 100 braccia over the land on either side. At its highest point, the arch would rise 70 braccia, or 43 m, above the water. While da Vinci was correct in asserting that a parabolic shape would offer extraordinarily strong support, the exact mathematical techniques required to build a bridge of this design were not developed until centuries later. These sketches, found in Manuscript L, are currently located at the Institut de France in Paris.


Atalay, B. (2013, January 22). LEONARDO’S BRIDGE: Part 2. “A Bridge for the Sultan”. Retrieved May 11, 2019, from

Books, Maps and Calligraphic documents in the Topkapi Museum. (n.d.). Retrieved May 12, 2019, from

C. (2011, April 10). Bridge built using Leonardo da Vinci's design for a self supporting bridge.Retrieved May 12, 2019, from (Originally photographed 2011, April 10)

The image is from Wikimedia Commons and taken by user Cntrading. It is used with the Free Art License.

circa. 3 Jul 1502 to circa. 3 Jul 1503 The letter is dated July 3, but the year is not specified

Letter to Sultan Beyazid II of Istanbul

While in Florence around 1502 or 1503, Leonardo da Vinci pursued a position as a scientist and engineer in the court of Sultan Beyazid II of Istanbul. To showcase his innovative ideas, he sent a “cover letter” to the Sultan proposing four projects: a windmill, a hydraulic pump, a bridge connecting Galata to Istanbul, and a suspension bridge across the Bosporus connecting Turkey and Asia. The bridge connecting Galata to Istanbul across the Golden Horn was da Vinci’s first formal proposal for a self-supporting arched bridge. As proposed, the bridge would be the longest single span bridge at the time and self supporting due to the parabolic shape of the arches underneath it. The sultan rejected this radical proposal and da Vinci’s design remained unused. The connection between this letter and da Vinci's sketches of the arched bridge design was established in 1952, as the letter, stored in the Istanbul National Archives, had been mislabeled and misattributed. The letter is now on display in the Topkapi museum in Istanbul.


Atalay, B. (2013, January 22). LEONARDO’S BRIDGE: Part 2. “A Bridge for the Sultan”. Retrieved May 11, 2019, from

Erik Cleves, K. (2014, April 8). [Galata]. Retrieved May 11, 2019, from

The image was taken by Erik Cleves Kristensen and is licensed under the Creative Commons Attribution 2.0 Generic license. It is provided through Wikimedia Commons.