Acha Mountain, located in the southeastern part of Seoul, is especially known for its beautiful cherry blossom trees both during the day and night.
It's the tallest mountain (287m) in Korea, but people are more of aware of its historical presence and significance as the Acha Mountain fortress where the three kingdoms- Goryeo, Silla and Baekje fought to get control of the Hangang river valley for 250 years. There's not much left of the fortress today.
Acha Mountain is now a park that offers walking trails and sports facilities. You can also get stunning views of the eastern Hangang river. It's also where Walkerhill hotel is located.
Photo in courtesy of http://cocoa2729.blog.me/50139237602
*2016 Walkerhill Cherry Blossom Festival will start in the mid of April. Dates haven't been confirmed yet.
Address
산52-2 Acheon-dong, Guri-si, Gyeonggi-do, South Korea