Mitau, Or Mittau (Russ. Mitavo; Lettish, Yelgava), a town of Russia, capital of Courland, situated in a low marshy district on the Aa, 25 m. S. W. of Riga; pop. in 1867, 23,-100, chiefly Germans, and including upward of 5,000 Jews. It is well built, and contains one Reformed, one Greek, one Roman Catholic, and three Lutheran churches, three synagogues, a gymnasium with a museum of physical science and natural history, a library, and various educational and charitable institutions, besides the buildings of the local authorities. Near Mitau is a palace built by Biron on the site of the original castle, after the model of the czar's Winter palace, where Louis XVIII. resided for a long time under the name of the count de Lille. There is an extensive trade in grain, flax, and linseed, which are sent hither from the interior of Courland and Lithuania for shipment on the Aa to Riga. The nobility of Courland reside here in winter, but Mitau is especially lively about St. John's day, when transactions are closed both by the nobles and the traders.