Today's Floridsdorf, Vienna's 21st District, with an area of 44.46m2, stands on land cultivated and developed by early man. The discovery there of stone axes suggests that it was inhabited as early as the Neolithic Age (ca. 4000 to 2000 BC). Celts settled here around 500 BC and the whole settlement area to the north of the Danube, known to the Romans as "Transdanubia", was fought over first by Germanic tribes and later by other invading peoples such as the Lombards, Avars and the Slavs. The settlement was initially called "On the Peak" ("Am Spitz") and belonged to the seminary of Stift Klosterneuburg. In 1786, the prelate at that time, Floridus Leeb, gave 30 plots along the Schlosshofer road to settlers and it is from him that the area takes its present name "Floridsdorf". What began as a predominantly agricultural area rapidly grew and developed as a result of the Nordwestbahn railway, flourishing industries and the steam tramway, which opened in 1885. In 1894 its status was elevated to that of a town.
In 1904 Floridsdorf, Jedlesee, Grobjedlersdorf, Donaufeld, Leopoldau, Kagran, Hirschstetten, Stadlau and Aspern were all incorporated into the City of Vienna, followed in 1910 by Strebersdorf. In 1938 Kagran, Stadlau, Hirschstetten, Aspern and Lobau were incorporated into the newly created 22nd district of Donaustadt. Under the redrawn boundaries of 1954, however, Stammersdorf was added to Floridsdorf.
Throughout the ages Floridsdorf's survival depended on the Danube as an important trading route. At the same time the raging torrent with its countless tributaries and branches wreaked havoc each year with severe flooding. It was not until 1870-1875 that measures were taken to regulate the Danube. Between 1972 and 1988 the high water defences were again reinforced so that Floridsdorf, like the other districts which border on the Danube, has since been protected from flooding.