Pirizen Fortress, Kosovo . This fort sits atop a deep gorge that gives access to the city plain, so is strategically located. There is also a hilltop castle one mile deeper into the gorge from here. I managed to fly the drone from one to the other. Links in comments.
paulianthomas says
[https://en.wikipedia.org/wiki/Prizren_Fortress](https://en.wikipedia.org/wiki/Prizren_Fortress)
[https://www.tripadvisor.co.uk/Attraction_Review-g304090-d2343948-Reviews-Kalaja_Fortress-Prizren.html](https://www.tripadvisor.co.uk/Attraction_Review-g304090-d2343948-Reviews-Kalaja_Fortress-Prizren.html)
[https://dtk.rks-gov.net/tkk_objekti_en.aspx?id=6229](https://dtk.rks-gov.net/tkk_objekti_en.aspx?id=6229)
[https://en.wikipedia.org/wiki/Monastery_of_the_Holy_Archangels](https://en.wikipedia.org/wiki/Monastery_of_the_Holy_Archangels)
[https://laurainkosovo.wordpress.com/2014/06/22/serbian-medieval-fortress-in-zupa-valley/](https://laurainkosovo.wordpress.com/2014/06/22/serbian-medieval-fortress-in-zupa-valley/)