Cheonggyecheon Stream is a historic artificial waterway that flows through the heart of the Jongno district in Seoul. It has undergone extensive restoration and has become a popular recreational spot, attracting both locals and tourists with its beautiful walking paths and vibrant urban oasis.
For a nice walk in the evening I recommend walking from Euljiro 3ga (or) 4ga-Station to the Cheonggyecheon Plaza and maybe walk up to Gwanghwamun Square.