This impressive riverside citadel is enjoying an ongoing renovation that's recreating its historic atmosphere. Look for the restored Nicholas Gate near the excellent Mark Rothko Art Centre. Built on the orders of tsar Alexander I on the eve of the Napoleonic wars, the fortress served as an imperial stronghold during two Polish insurrections in the 19th century and as a home away from home for tsars exploring their realm. It's a 3km walk northwest of the centre along the river.

　　Although the architecture is rather utilitarian, you can make out Gothic and Egyptian motives in the decor of its four gates – all named after Russian royals. The fortress itself survived two centuries of wars and revolutions largely intact, but the beautiful 18th-century Jesuit cathedral that stood in the middle was destroyed by WWII bombardment, its ruins later cleared by the Soviets, who instead built a cluster of ugly generic apartment blocks for the military. A plaque outside the main gate states that Tatar poet Musa Jalil languished here from September to October 1942, in what was then the Nazi concentration camp Stalag-340. Inside, a memorial marks the site where local aristocrat Leon Plater was executed by the tsar's soldiers for leading the Polish revolt in the area in 1863.