[3][4] The town is located on both banks of the River Lahn, the natural border between the Taunus and the Westerwald, two parts of the Rhenish Slate Mountains.

In Roman times, a castrum was built at Bad Ems as part of the Upper Germanic Limes, but today not much of the structure remains.

It reached its heyday in the 19th century when it welcomed visitors from all over the world and became the summer residence of various European monarchs and artists, including Kaiser Wilhelm I of Germany, Tsars Nicholas I and Alexander II of Russia, Richard Wagner, Fyodor Dostoevsky and Vasili Vasilyevich Vereshchagin, etc.

In 1876, in the Haus Vier Türme (Four Tower House), the Ems Edict was signed by Alexander II of Russia, banning the use of the Ukrainian language.

In the 19th and 20th centuries a lot of mining for metal ores took place in the town, concentrated on lead, silver, zinc and copper.

The advent of the Industrial Revolution led to the expansion of the mine, which from 1871 operated under the name of Emser Blei- und Silberwerk AG (Bad Ems Lead and Silver Works, Inc.).

Industry in Bad Ems is mainly limited to companies related to its spa status, but nonetheless fairly varied, including medicine, electrical engineering and tourism.