Trolza (Russian: ZАО "Троллейбусный завод" (Тролза)) is a trolleybus producer in Russia, located in Engels, Saratov oblast. In the Soviet era it was known as ZiU (Russian: Завод имени Урицкого, Zavod imeni Uritzkogo, plant named after Moisei Uritskiy). The enterprise was founded in Imperial Russia in 1868, but it began producing trolleybuses after 1951. ZiU/Trolza built over 65,000 trolleybus vehicles and continues this business now.