It is a tour bus that departs from Gwanghwamun and goes around Mapo-Banpo-Hannam-Seongsu Bridge-N Seoul Tower and returns to Gwanghwamun. (Please buy tickets in advance!)

You can enjoy the night view of the Han River without any blockage by driving on the bus lane. It has a 30-minute stop at N Seoul Tower, so it's good to take pictures during that time.

Image Source

1. Seoul City Tour Bus official website

2. Seoul Metropolitan city hall official website