Wienfluss-Portal, Bridge structure in Stadtpark, Vienna, Austria

The Wienfluss-Portal is a monumental ensemble of two square, open pavilions with domes, built where the Wien River emerges from its underground course at the southern entrance of Stadtpark. Stairs lead from the pavilions down to the river quays, and the left bank wall features high-relief statues of the seasons by Franz Klug and niches with cobalt-blue vases designed by Friedrich Ohmann.

The Wien River repeatedly flooded Vienna, with major floods recorded in 1295, 1405 and 1670 and about 25 floods between 1805 and 1899. Regulation works ran from 1894 to 1904 alongside Otto Wagner's Stadtbahn. Rudolf Krieghammer first conceived the monumental complex; after his death in 1898 Friedrich Ohmann took over planning, with Josef Hackhofer as assistant from 1900. Building permission was granted on 21 January 1903, construction lasted until 1906, and the monument was inaugurated on 15 November 1906.

The portal marks where the Wien River leaves its covered channel and enters Stadtpark. Its two domed pavilions and the quays between them were built by Friedrich Ohmann and Josef Hackhofer in 1903–1906, next to Otto Wagner's Stadtpark station. On the left bank wall, high-relief female figures by Franz Klug represent the seasons, set between niches holding cobalt-blue vases designed by Ohmann.

The portal stands at the southern entrance of Stadtpark on Johannessgasse, beside the Stadtpark U-Bahn station in Landstraße. Stairs at the foot of the two domed pavilions lead down to the quays along the Wien. The gate columns of the entrance frame the site from the street side.

The portal and one pillar of the Johannesgasse gate appear on a 100-euro gold coin issued in 2006. Five of the six cobalt-blue vases designed by Friedrich Ohmann were destroyed in World War II and later rebuilt. Ohmann's plan for a waterfall in the arch and elephants spouting water was never realised.