Arabat Fortress built
1700 CE.
Shown on the map at 45.296°, 35.478°.
The Arabat Fortress, built in the 17th century by the Ottoman army, stands at the southernmost part of the Arabat Spit. Its purpose was to guard the spit and Crimea from invasions. It was in use, with intermissions, until the Crimean War of 1853–1856.
Text from the Wikipedia article Arabat Fortress, licensed CC BY-SA 4.0.