After passing Vienna and Marchfeld, the river cuts through a defile
formed by the lower spurs of the Alps and Carpathians and enters Hungary
at the ruined castle of Theben, a little above Pressburg, the old Magyar
capital. Here, again, it gives off a number of branches, forming a
labyrinth of islands known as Schütten, but on emerging it flows
uninterruptedly southward through wide plains interspersed with pools,
marshes, and sandy wastes. The principal affluents here are the Save,
the Drave, and the Theiss.
Sixty miles before entering Roumania the river passes through a
succession of rapids or cataracts which it has made in cutting a passage
for itself through the cross chain of hills which connect the Carpathian
Mountains with the Alps. The last of these cataracts, at Old Orsova, is
called the Iron Gate. Between 1878 and 1898, the Hungarian government
carried through, at a cost of seven million five hundred thousand
dollars, extensive engineering works at the gorges of the Iron Gates for
deepening the channel and cutting a canal.