The Rhine is Europe's best-known river. Running through the heart of Europe, it touches six countries as it flows from Switzerland to its mouth in the Netherlands. From Roman times onward, the Rhine was used for trade, and the cities along its banks became rich and powerful. Today, the river is still full of traffic, providing a lifeline for modern industries. Until the 1980s, the Rhine River suffered from flooding and pollution, but these problems have been largely overcome. Today, the Rhine annually attracts thousands of tourists who vacation on the river and visit its ancient cities and romantic castles.