Yes that is Hooker Hill. There are 3 primary locations "Red Light Districts" in Seoul, and probably 2 of them are foreigner friendly. Itaewon and Yongsan are the ones that most foreigners go to. If you are korean, then you can go to Miari but for the most part, stick with the 2 former. Yongsan "red light light district" is right outside the subway station, so it's like a block away lol. and you will see a bunch of windows ang girls posing in front.
As for Itaewon, it's the foreigner district, and like JayDubb said, it's gonna be easy to get the girls (watch out for the T-girls as well because the bars are right next to each other) but for the most part, they will let you in, talk to them, buy them a lady drink (about 5-10k won ~ $5-10) and have fun. Usually they are in the 150-200k range ~ $150 - $200) but you can haggle the price if you're willing.
This information is pretty recent as I was there less than a year ago and stayed in Korea for about a year. I lived in Busan however, so I only occasionally went to Seoul from time to time. I do know the Busan area well, so if you need more info on that, then just ask away.
BTW, here's the map of hooker hill provided by the U.S army
http://www.usfk.mil/usfk/Uploads/330/USAG-YItaewonMaps01June09.pdf