A brine spring (Soolquelle) at the foot of the neighbouring Domberg is said to have given name to the town.
Of the river, and the more important buildings are clustered round the two eminences known as the Domberg (cathedral hill) and the Schlossberg (castle hill), which in the middle ages were occupied by the citadel, the cathedral and the episcopal palace.
The city consists of two parts-the Domberg or Dom, which occupies a hill, and the lower town on the beach.
The high Silurian crag now known as Domberg was early occupied by an Esthonian fort, Lindanissa.
On the south-western side of this square, which contains a monument to the elector Frederick Charles Joseph of Mainz (1719-1802), is the Domberg, an eminence on which stand, side by side, the cathedral and the great church of St Severus with its three spires (14th century).