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Yeoju Weir

Hangang Bike Path
Learn about Yeoju Weir, a watergate designed after Korea’s most important king.

Opened in 2011, Yeoju Weir (Yeoju-bo; 여주보; map) is the second Four Rivers Project watergate on the South Han River. Like Ipo Weir 13 kilometers north, Yeoju Weir’s unique design reflects the city where it lives.

Let’s explore!


Yeoju Weir is the 4th Scenic View of the South Han River. Its architecture commemorates the legacy of King Sejong the Great (1397~1450), Korea’s most important ruler. His tomb rests two kilometers down-path on the edge of downtown Yeoju City (여주시; map).

King Sejong supported science. He pushed the Joseon Dynasty (1392~1897) into the future by creating Hangul (한글), Korea’s written alphabet, and supporting innovators like Jang Yeong-sil (장영실; 1390 ~ 1442), a scientist who was born a peasant. 

The bike path on the Yeoju-bo weir on the Hangang Bicycle Path
Yeoju-bo is the last weir you’ll cross before Yeoju. The design of the supports represent the inventiveness of King Sejong.

Three famed inventions created under King Sejong’s reign inspired Yeoju Weir’s design:

  • Twelve pairs of glass pillars stand on the weir’s top deck. They resemble a Jagyeongnu (자격루), or water clock, invented by Jang Yeong-sil.
  • Concentric circles on the weir’s concrete supports were molded after an Angbuilgu (앙부일구), or hemispherical sundial, created by Jang Yeong-sil and two other scientists during King Sejong’s rule.

A copy of the Hunminjeongeum document appears on the side of the weir’s hydroelectric plant. Published in 1446, the document described how to use the newly invented Hangul (한글) writing system.


The twelve pillars on top of Yeoju Weir aren’t just decoration. They raise and lower the weir’s twelve 8-meter-tall water gates, regulating the South Han River’s flow.

Perched on the west end of the weir’s 525-meter span sit three small hydroelectric generators. They create 29.7 kWh of energy per year, enough to power 6,750 households.

Sundial Island

A perfectly round island lies under the east end of Yeoju Weir. From above, it also imitates an Angbuilgu (hemispherical sundial; map).

  • A spiky tower sitting on top of Yeoju Weir is the gnomon, or the shadow-casting needle of a sundial.
  • The parabolic walking paths on the island mimic the hour lines of a sundial.

A small inlet on the north side of Sundial Island siphons off water from the South Han River. It features a set of tiered steps that wrap around the manufactured island. Migrating fish can bypass Yeoju Weir’s watergates by hopping up or flowing down the steps.

Want to explore this concentric island? Ride an elevator tucked inside the spiky gnomon tower down to Sundial Island (road view). Then stroll the island’s perimeter, relax on an outdoor stage, or cast a line and wait for something to bite.

Yeoju Culture Center

Yeoju Weir Cultural Center (여주보문화관; map) occupies the west bank of Yeoju Weir. Open from 9 AM to 6 PM (closed Mondays and holidays), the three-story center holds a wealth of facilities.

Yeoju Weir Observatory

Yeoju Weir Observatory (여주보전망대) sits beside the culture center. Like the glass pillars installed on the weir, the tower’s tapered form resembles a Jagyeongnu (자격루), or water clock invented under Sejong’s reign.

Open every day from 9 AM to 8 PM, the 40-meter tall tower offers an elevated view of Yeoju Weir and the South Han River. Between summer and fall, the fields below display rice paddy art (단보아트).