COEX, the COnvention EXhibition Center, is a convention, business, and entertainment hub in central Seoul. The prominent buildings seen in the top photo are COEX Intercontinental Hotel (photo left) and the Korea World Trade Center (photo right, also called the World Trade Tower), built in 1988. The extensive COEX Mall is belowground. The "main street" is Samsung Dong (also spelled Samseong Dong), and the district is Gangnam (the central business district of Seoul). The bottom photo is another view of the same area.
The architectural form of the KWTC closely resembles the Trump Tower in Chicago.