'Tulln on the Danube') is a historic town in the Austrian state of Lower Austria, the administrative seat of Tulln District.

Although it was settled in pre-Roman times (the name Tulln is presumably of Celtic origin), it gained importance as the Roman fort of Comagena (Comagenis).

On 6 September 1683 the Polish cavalry of King John III Sobieski united here with Imperial (Austrian) forces, as well as troops from Saxony, Bavaria and Baden for the Battle of Vienna against the invading army of the Ottoman Empire.

The 20th century was another period of growth, and in 1986, Tulln applied to become capital of Lower Austria, although Sankt Pölten eventually won.

Various state institutions of Lower Austria, such as the fire brigade or the disaster relief service, have their seat in Tulln.