Yverdon-les-Bains (ēvĕrdôNˈ-lā-bĕNˈ) [key], Ger. Iferten, town (1990 pop. 22,758), Vaud canton, W Switzerland, at the south end of the Lake of Neuchâtel. It is an old spa with Roman ruins. Machinery, precision instruments, and tobacco products are manufactured in the town. Heinrich Pestalozzi held (1805–25) his experimental classes in the town's 13th-century castle.