Tulln an der Donau (Tulln on the Danube) is a historic town in the Austrian state of Lower Austria, the administrative seat of Tulln District. Because of its abundance of parks and gardens, Tulln is often referred to as Blumenstadt ("City of Flowers").

The town is situated in the centre of the Tulln Basin stretching to the Vienna Woods in the south, about 40 kilometres (25 mi) northwest of the Austrian capital Vienna. The main part of its built-up area is located on the southern bank of the Danube river.

The municipal area comprises the cadastral communities of Frauenhofen, Langenlebarn-Oberaigen, Langenlebarn-Unteraigen, Mollersdorf, Neuaigen, Nitzing, Staasdorf, Trübensee, and Tulln proper.

Sights include:

• Altar of Minoriten-Church
• According to the Nibelungenlied, it was in Tulln that Attila the Hun saw Kriemhild (the Nibelungenlied's name for Gudrun) and proposed to her. A fountain, the Nibelungen-Brunnen ("the Nibelungen Fountain") was dedicated to this event in 2005.
• The ship Regentag by Friedensreich Hundertwasser is riding at anchor by the Danube as a part of a modern art museum here since 2004. It was first heard of in the short documentary Hundertwasser's Rainy Day (1972).
• In 2008 a shopping mall, called Rosenarcade was built.
• Aubad is a well known lake in Tulln with many visitors and tourists during spring and summer time.
• Minoritenkloster, a convent.
• A 4th-century Roman tower.