'N' from Seoul Tower stands for New, Namsan and Natural Seoul Tower. Most visitor ride the Namsan cable car up the mountain, and the walk to the tower.
According to Wikipedia, The Tower built in 1969, and opened to the public in 1980, the tower has been a symbol of Seoul and measures 236.7 m (777 ft) in height (from the base) and tops out at 479.7 m (1,574 ft) above sea level.
The tower features a gift shop and restaurant on the ground floor. Visitors may go up the tower for a fee.
There are four observation decks (the 4th observation deck, which is the revolving restaurant, rotates at a rate of one revolution every 48 minutes), as well as gift shops and two restaurants.
View N Seoul Tower - South Korea in a larger map
There is also a personal media play zone where you can check out the latest movie trailers and music videos, pavilion exhibition halls where various cultural events are held, and a roof terrace where you can enjoy a scenic view of Seoul.
It is a popular place to go on clear days to se most of Seoul.