Belgrade Fortress, a sprawling historical and recreational complex, is highly accessible for most visitors, serving as a vast open-air museum and park known as Kalemegdan. It's ideal for both solo exploration, allowing visitors to wander its ancient walls and green spaces at their own pace, and guided visits which offer rich historical context, often available through free walking tours of Belgrade. The site is open year-round, though spring and autumn offer the most pleasant weather for extended outdoor walks. Entry to the main fortress grounds and Kalemegdan Park is free, with separate, modest fees (typically a few euros) for specific attractions like the Military Museum, Roman Well, or Belgrade Zoo. A typical visit duration ranges from 2 to 4 hours to comfortably explore its various sections, admire the panoramic views of the Sava and Danube rivers, and visit points of interest like Ružica Church and St. Petka's Chapel. Comfortable footwear is recommended for navigating the extensive grounds.