An impregnable fortress

This fortress is called Smederevo Fortress. Which is located in the city of Smederevo at the confluence of the two rivers
Jezava into the Danube. It was built in the 15th century. It had 5 phases of construction. It was built by Despot Djuradj Brankovic after the fortress named Djuradj Smederevac. The fortress is flat and one of the largest and perhaps the largest in Europe. The fortress was surrounded by two rivers and a canal was dug in the very south of the fortress. So the fortress was located on an artificial island.

It consists of two parts. The first and smaller part is a small city and is in the shape of a small triangle, the second part is a large city. The fortress is in the shape of a triangle. The ruler lived in a small town with his family, while the rest of the population lived in a big town. It was built on the bed of the Constantinople fortress.

There were 4 Serbian phases of construction and 1 Ottoman phase of construction of the fortress.
The first phase was the most important for the despot and his family. Because in the first phase, a small town was built and the despot's court was in it.

The construction lasted from 1428 to 1439. The small town had 6 towers and the ruler was housed in it. But it was clear that this was not enough, so they decided to build the rest of the fortress as well.

There is no exact source when the rest of the city was completed. But during the Ottoman army's attack on the city, they could not conquer it, which means that the city was finished.
The city was so strong and invincible that the Ottoman army could not conquer it. So they decided to besiege it for three months and attacked it with their cannons every day.

Three months later, on August 18, 1439, the Serbian army surrendered due to food shortages. The Ottoman army occupied the city.

Before the siege of the city, the despot withdrew to the then kingdom of Hungary, in order to gather an army to regain his state. When he gathered his army, he set out to return his country, where the crusader warriors also helped him. When he regained his territory, the despot signed peace with the Ottoman Empire in 1444. That is how the Smederevo Fortress again became the capital of Serbia and the despot Djurdj Smederevac

Thus we come to the second phase of the construction of the fortress. When the despot covered your towers and built a granary in a small town.

After that, we come to the third phase, when small walls were erected on the banks of the rivers on the left and right.

In the fourth phase, towers were added to the small walls facing the Danube

The fifth phase of construction was carried out by Ottoman soldiers who added 4 small artillery towers, one at each exit of the fortress and one at the very south of the fortress, and it formed a gate to the city.

After several unsuccessful attacks by the Ottoman army, the fortress was conquered in 1459, which was the formal end of the Serbian medieval despotism.

The fortress was not returned to Serbian possession until 1867, thanks to the withdrawal of the Ottoman army. Since then, the fortress has a shape that we can see even today.