Viby, often referred to as Viby Sjælland (usually styles Viby Sj) to distinguish it from Viby J in Jutland, is a satellite town to Roskilde and Copenhagen, located 8 km south of Roskilde, in Roskilde Municipality, some 30 km west of Copenhagen, Denmark. The original village, now Gammel Viby ("Old Viby"), is located in the northn part of town while the modern district has formed around Viby Station which opened on the Danish Main Line between Copenhagen and western Denmark in 1854.