Znak Pitanja — the Question Mark — is believed to be the oldest restaurant in Belgrade, having operated on this site since 1823. The interior is a wood-panelled, low-ceilinged room that looks authentically old, and the menu is traditional Serbian: bean soup, grilled meats, roast lamb, burek, and a reliable house wine. The prices are moderate and the atmosphere is genuine rather than performed.
The location on Kralja Petra, just off Kalemegdan and steps from the Cathedral, makes it the natural lunch stop after a morning at the fortress. It fills up with locals at midday and early evening. The story of the name is told on a small plaque inside, and the owners take justifiable pride in the continuity — though the food has clearly evolved somewhat over the past two centuries.