The Citadela occupies the southern tip of Budva’s Old Town, the highest and most defensible corner of the peninsula, built up over centuries of Venetian and later Austro-Hungarian rule. Where the rest of the walled town is free to wander, the fortress is the one place with a ticket gate, and it earns the entry.
The reason to pay is the ramparts. From the sea-facing walls you get the widest view in the Old Town: the sweep of the riviera, the open Adriatic, and Sveti Nikola island sitting squarely in front. It is the photograph everyone takes home, and late afternoon light is kindest to it.
Inside the walls the attractions are small but likeable: a maritime museum with a collection of model ships, a historic library with a quiet reading room, and a terrace cafe-restaurant where you can sit within the fortress itself. None of it takes long; 30 to 60 minutes covers a visit at an unhurried pace.
Tickets are sold at the gate and the fee changes seasonally, so check the posted price when you visit. Combine it with a loop of the town walls and the lanes below, and you have the complete Old Town in a single afternoon.