Namsan Park
The Namsan Park is the largest park in Seoul and houses the N Seoul Tower at its peak. You can reach the top by cable car or hike up there with the locals. We chose the hike because it was a beautiful day and we could fully enjoy the scenery. The trail was about 2km (about 230m high) and took us (with the kids) about 45 minutes and it was all worth it. Part of the trail can be a little steep for some people.
N Seoul Tower
As a reward for reaching to the top of Namsan Park, you get to see the N Seoul Tower. It was featured in the famous Korean TV drama, My Love from the Star and is one of the most famous attractions in Seoul. The N in its name stands for Namsan. Once you are at the top, you can reward yourself with a scoop of ice cream-or bubble tea-and games organized by volunteers.
Han River
A major river dividing the Seoul city, Han River is an excellent place to relax and take a stroll (or ride a bike). Both sides of the river were well developed with elevator for bikers and art displays along the way. There were bike rental shops along the way. Fortunately for us, our hostel provided free bicycles and it was close to the Han River. So we took advantage of it. It was an amazing experience that I wouldn't mind doing it everyday.