The English missionaries Willibrord (Willibrord, Saint) and Adalbert preached Christianity in the district in the 8th century. A fishing village in the 10th century, Alkmaar (possibly meaning “all marsh,” “all sea,” “all lake,” or “auk lake”) was chartered in 1254 and was the capital of Kennemerland, an early possession of the counts of Holland. It was sacked by the Frisians in 1132 and again by a combined force of Frisians and Gelderlanders in 1517. Alkmaar became an important trade centre after 1564, when the surrounding swamps were reclaimed. The town successfully withstood a Spanish siege in 1573 to become a symbol of Dutch resistance (commemorated by a monument in Victorie Park). Under the Convention of Alkmaar (1799), a Russo-British army withdrew from the Netherlands after an unsuccessful campaign to overthrow the Batavian Republic.

A market centre for cattle, dairy products, and vegetables, the town is also a tourist centre noted for its Friday cheese market (Kaasmarkt), held from April to October. Alkmaar's manufactures include furniture, clothing, paper, and church organs. The most notable landmarks are the Weighhouse (1582, rebuilt from a 14th-century chapel), with a carillon tower, and St. Lawrence's Church (1470–1520), with one of the oldest organs in The Netherlands (1511). Other historic buildings include the town hall (1520), the 16th-century Sonoy Court, and several almshouses. Pop. (2007 est.) 94,174.