Above is an old map of south east Europe. If you look at the backwards “c” shape of the Carpathian Mountains, you can look for cities of Brasov and Sibiu. These two fortified cities held off the Green Flag of the Ottoman Turks from going further north into Europe. The Emperor of the Austro-Hungarians placed seven citadels in the Carpathians, specifically to stop the Turks.
Today the Romanian cities are tourist attractions. The German immigrants who built the citadels did an amazing job. Beautiful huge walls, churches, schools, etc. They lived in Romania, but lived completely separate lives within the walls of these cities. As you can see from the photo below, Brasov was strategically placed in a tight valley. This made it easier to defend.
The Romanians today owe much to these German settlers. The beautiful old cities bring in many tourist dollars.