Blida (blēˈdä) [key], town (1998 pop. 226,512), N Algeria, at the foot of the Mitidja Atlas Mts. The name also appears as El Boulaïda. It is an administrative center and an agricultural trading town. Blida is surrounded by gardens and by orange, olive, and almond tree plantations. Wheat, barley and tobacco are also grown. The city is noted for its fruit and flower essences. Built on the site of a Roman military base, Blida was founded in 1553 by Andalusians, who developed irrigation works and orange cultivation. Most of the old town was destroyed by earthquakes in 1825 and 1867.