Movable bridge (lifts) across the Zijl and my favorite Eastern access to Leiden. The bridge is from 1933. The explanation of the name of the bridge (Spaniard's bridge) can be found below.
From Wikipedia:
On May 26, 1574, the Spaniards came with ships across the Haarlemmermeer to the "Spanjaerdsbrug" to besiege Leiden. The name of the bridge comes from the time when a redoubt was located against the Spaniards. The Spaniards had made a large army camp in Leiderdorp. As soon as the Spaniards had left, this camp was cleared by Leiden. The bridge did not survive the Spanish occupation and was subsequently restored and rebuilt several times. In 1891 the bridge was renovated and in 1931 "Het Zijlhek", where tolls were levied, was abolished. A new bridge was built in 1933 (current bridge). The bridge and the bridge house both have the status of national monument. They have been registered in the monument register since 2000.