Sillian is a market town in the district of Lienz, in the Austrian state of Tyrol. It lies in the eastern part of Tyrol, in the Puster Valley (Pustertal) near the border with Italy's South Tyrol.
The town is situated in the valley of the Drava (Drau) river, which flows through the Puster Valley. Sillian serves as a local administrative and service centre for the surrounding area, and its status as a market town (Marktgemeinde) reflects its historical role as a trading and gathering place in the valley.
Sillian is known in the region as a base for outdoor activities in the surrounding Alpine landscape, including hiking in summer and skiing in winter, with the nearby mountains of the Carnic Alps and the Villgraten Mountains forming the backdrop to the town.