Besides the greening of Seoul in recent years another major change to the city is the restoration of various historical sites in particularly the walls around Seoul which is something I have been a supporter of for many years:

From Gwanghwamun Square to Seoul Station and the new City Hall, the city has been home to many restoration and development projects in recent years at a number not seen since the Park Chung Hee administration.

In the 1970s, the dictator restored historic structures by arguing that they were related to the important issue of national defense.
But in the ensuing decades that brought regime changes and tumultuous democratization movements, preservation efforts simply weren’t a priority for the government or everyday people.

Its efforts are buoyed by increased awareness of cultural properties and the recent Unesco recognition of several Korean heritage sites, including the royal tomb in 2009, as well as by the return of stolen relics, like the case of the Uigwe royal protocol books last year.

Early this month, the government announced that it will continue such initiatives by restoring the Seoul wall by 2015.

“Korea is the only existing castle city in the world,” Mayor Park Won-soon said. “With the restoration, the Seoul wall will be a place of pride and an attraction for foreign tourists.”   [Joong Ang Ilbo]

You can read much more about the restoration of the various historic sites at the link.  I have always felt that the Seoul government should restore the old fortress walls in order to give the city a unique feature unlike any other major city in Northeast Asia to make it stand out.  As it is right now there is no feature of Seoul that pops to mind that international tourists would want to see.  The fortress walls would definitely be a unique attraction especially if it becomes a popular thing to hike the length of the walls while visiting the country.