The traditional heart of Seoul is the old Joseon dynasty city, now the downtown area, where most palaces, government offices, corporate headquarters, hotels, and traditional markets are located. Cheonggyecheon, a stream that runs from west to east through the valley before emptying into the Han River, was for many years covered with concrete, but was recently restored by an urban revival project in 2005. Jongno street, meaning "Bell Street", has been a principal street and one of the earliest commercial streets of the city, on which one can find Bosingak, a pavilion containing a large bell. The bell signaled the different times of the day and controlled the four major gates to the city. North of downtown is Bukhan Mountain, and to the south is the smaller Namsan. Further south are the old suburbs, Yongsan District and Mapo District. Across the Han River are the newer and wealthier areas of Gangnam District, Seocho District and surrounding neighborhoods.