belgrades historic fortress rises above the sava river in vibrant autumn colors

belgrade fortress savariver autumn trees historical architecture landscape boats colorful serbia vibrant cityview riverbank tourism skyline travel nature culture heritage sightseeing outdoor scenic mountainous urban picturesque sunset buildings peaceful waterfront historicalsite exploration journey citylife skylineview photooftheday rivercruise adventur wanderlust vacation medieval artwork oldtown view scenicspot travelphotography idyllic culturetrip attraction riverfront