The Zócalo in 1521
Just before the Spanish conquest, this is what the magnificent ceremonial center of the Aztec capital of Tenochtitlán looked like. The large structure to the rear was the main temple. There were two shrines atop the pyramid. The blue one was dedicated to Tlaloc, the rain god; the red one was the shrine of Huitzilopochtli, the god of war. The excavated foundations of the temple are today next door to the Cathedral of Mexico City.
The Zócalo in 1824
Mexico had just won its independence a few years before, and the Zócalo still looked the same as it did in the colonial period. The recently completed Cathedral, the largest in the New World is to the left. Within the circle on the plaza the statue of King Carlos IV of Spain still stood, although that symbol of colonial rule would soon be removed. A good portion of today's Zócalo was taken up by the Parián Market building (just below the circle). The long building above the circle had been the Viceroy's Palace during colonial times, and became the National Palace after independence.
The Zócalo in 1900
Mexico entered the 20th century under the dictatorship of Porfirio Díaz. Díaz wanted to make the capital a modern city. As you can see trolley cars ran around the Zócalo. Trees and gardens were planted in the middle of the plaza.