UPDATE: 1) See this post for a recent visit to SkyArt, featuring a Picasso exhibit: 63 Building and Picasso.
2) See this post for upgrades to Yeouido park and a slideshow showing the progression through the seasons of the year: Changes at Yeouido Park.
Yeouido 여의도, which roughly translates as 'island of wishes', is the location of Seoul's CBD and National Assembly (domed building above). There is also a large park splitting the island in two. The south tip is famous for the 63 Building, reputed to be the tallest in Korea--though it is outranked by both the Samsung Tower Palace 3 and Mok-dong Hyperion I Tower A.
Yeouido Park: Long and skinny, divided into three sections, this is a nice place to while away an afternoon, with nature areas, walking trails and bike paths (and bike rentals--or inline skates or rocker boards, if you prefer). Clockwise: Park sign at southeast entrance; one of many magpies attracted to the grassy field; carp pond; a carp in the carp pond; intrepid explorer Gavin walking through the traditional Korean forest; the Palgakjeong pavilion at the highest spot in park.
King Sejong Statue: King Sejong 세종대왕 was the third emperor of the Joseon dynasty (1379-1450), and is rightly revered for many intellectual achievements. Though probably most famous for developing Hangeul, the phonetic alphabet still used for Korean language, sundials, water clocks, and even the first rain gauge were developed during his reign.
This monument takes note of these achievements with replica rain gauge (which I previously mentioned here), sundial and (I guess) water clock on three corners; there are also tile stele commemorating episodes from his life. It's not the Lincoln Memorial, but it's a nice niche.
Here is an image I took of a working water clock at the National Palace Museum next to Gyeongbokgung. It is full size, and was shot from an observation room on the next floor up:
63 Building: Me, with the east view behind, then northeast, north, and west. The long green building in the west view is the Noryangjin fish market.
In addition to amazing views of metro Seoul, the 63 Building observation deck offers "SkyArt"--well, not so much offers as requires, since you have to buy a SkyArt ticket in order to get up here. Advertised as "the highest art gallery in the world" it has a couple of interesting pieces among the dreck, notably this Andy Warhol:
Gotta love the giant snails, too; and what's the world's highest art gallery without flying pigs?
The 60th floor provides other amenities, including a "Thrill Deck" whose mirrors and prisms will make you dizzy ...
... SkyFun, a children's play area ...
... and the SkyArt Cafe, where we sipped a couple of beers at reasonable prices before heading back down to terra firma.