When I go to a city I've never visited before, I always look for the highest building I could visit. I really like the view you can have from the top floors of skyscrapers, that's why I love the Oriental Pearl Tower of Shanghai and the One World Observatory in New York.
The Lotte World Tower isn't really high, compared to other buildings like the Burj Khalifa, but it offers so many opportunities to enjoy your time there.
The Lotte World Tower is located next to the Lotte World Mall, a great place to go shopping and have lunch or dinner. From here you can easily find the entrance to the tower by following the signs in the mall.