Bacau, city in eastern Romania, on the Bistrita River. It is the capital of Bacau County and a railway junction and industrial and trade center for petroleum products, fruits, and nuts. Manufactures of the city include textiles, machinery, hardware, leather, and earthenware products. In the vicinity of Bacau are flour mills, meat-processing plants, major paper and pulp mills, and several large hydroelectric plants. The city has two 15th-century churches and a cultural museum. During World War I (1914-1918), Bacau served as headquarters for the Romanian army. Population (1997 estimate) 209,689.