Georgetown is a city and also the county seat of Williamson County, Texas, United States with a population of 47,400 at the 2010 census. Southwestern University, founded in 1840, is the oldest university in Texas and is located in Georgetown, about 1/2 mile east of the historic square. Sun City Texas (formerly called Sun City Georgetown) is a large retirement-oriented and age restricted development which constitutes more than one-third of the population of Georgetown. Georgetown has a notable range of Victorian commercial and residential architecture. In 1976 a local historic ordinance was passed to recognize and protect the significance of the historic central business district and in 1977 the Williamson County Courthouse Historic District, containing some 46 contributing structures, was listed on the National Register of Historic Places.