There are lots of interesting sites around the citadel, where the big Vietnamese flag tower is based. The entire Hue is rich in culture and ancient buildings. The citadel city is alive during the day and during the night, where one finds lots of restaurants, fruit markets and rickshaw drivers. The entry to the citadel is free, however, the fees are chargeable to the historic sites where you'll learn about the Royal family that use to live here. You may want to rent a bicycle to ride around the town, to take few photos of many pagodas, or while admiring many green landscapes and parks around the city. Hue is fairly green, with lots of parks where you can walk or even view the big river which flows through the middle of the town. I would also recommend shopping at the local street markets, as there areany of them around and where one can purchase many local fruits or fresh coconut. Not to far from Hue is a hot spring, while you can also take a ride or a taxi to the beach.