Wongwian Yai, also spelled "Wong Wian Yai" or "Wongwien Yai" (Thai: วงเวียนใหญ่), is a large roundabout (traffic circle) in Thonburi, on the west bank of the Chao Phraya River in Bangkok, Thailand, where the statue of King Taksin is situated. It is in the Thon Buri District and Khlong San District in the centre of Bangkok, at the intersection of Prajadhipok/Inthara Phithak/Lat Ya/Somdet Phra Chao Taksin Roads. Nearby is Wongwian Yai Station, a historical commuter railway terminal to Mahachai (local name of Samut Sakon provincial city) and Mae Khlong (Samut Songkhram), a southwestern suburb of Bangkok.
The circle was built following the Memorial Bridge (Phra Phutta Yodfa Bridge) opening on 6 April 1932, commemorating the 150th anniversary of the Chakri Dynasty and Bangkok City. The bridge from old Bangkok conducted 11 new road projects to be built on Thonburi side of the Chao Phraya River, also with the circle. It was named Wongwian Yai, "big circle" in Thai, as there was a smaller traffic circle with clock tower next to the Memorial Bridge called Wongwian Lek, "small circle". The statue of King Taksin was built 21 years later.
As a memorial to Taksin the Great, one of the great Thai kings who liberated the country after Ayutthaya was taken by the Burmese in 1767, the statue was built here in 1953, on the Thonburi side of the river where the king had established a new capital in 1768. The statue was created by the Italian sculptor Corrado Feroci, who worked under the Thai name Silpa Bhirasi. A state ceremony on a day of homage to the king, 28 December, has been held annually since 1954.
The circle is one of Bangkok's major traffic intersections, linking residential areas on the Thonburi side to Bangkok's downtown via the Memorial Bridge in the north. The northeastern road, Lat Ya, links Khlong San Pier with ferry service to Si Phraya Road or the further Taksin Bridge to Sathon and Si Lom business clusters. The southern road, Somdet Phrachao Taksin (or Taksin Road), links to suburban areas on Suk Sawat and Rama II Road and reaches Chulachomklao Fort at the river's mouth in Samut Prakan Province. The western road, Inthara Phitak, is important as it links to the beginning of Phet Kasem Road, the highway to west and south Thailand. At the southwest corner of the circle, there is a commuter railway station to Samut Sakhon Province.