Nampo is North Korea's main port city, sitting at the mouth of the Taedong River on the west coast, about 50km from Pyongyang. Most of the country's seaborne trade passes through here, and the city has a functional, working feel that is a world away from the capital's monumental theatrics.
The one sight worth your time is the West Sea Barrage: an 8km dam and lock system completed in 1986 that tames the tidal mouth of the Taedong and delivers fresh water to the Pyongyang plains. The engineering is genuinely impressive on the ground, and it shows up on virtually every extended tour itinerary as a half-day excursion from the capital.
Beyond the barrage, Nampo is an industrial and port city without the ideological set-pieces of Pyongyang or the historical weight of Kaesong. Come to see the barrage; don't expect much more.