A pedestal with no statue
In the 19th century a monument to independence was planned for the center of the square, but only its base, the zócalo, was ever built. The name stuck, and today squares all over Mexico are called zócalos.
One of the largest squares in the world sits on top of the Aztec capital, framed by the cathedral and the National Palace. Here's what you're looking at, and what to listen for when you get there.

In the 19th century a monument to independence was planned for the center of the square, but only its base, the zócalo, was ever built. The name stuck, and today squares all over Mexico are called zócalos.
The Metropolitan Cathedral took from 1573 to 1813 to finish, which is why it mixes Renaissance, Baroque and Neoclassical styles. It's the largest cathedral in the Americas.
Every 15 September at night, the president rings the bell from the National Palace balcony and leads the "Grito" of independence to a square packed with people.
Zócalo means pedestal: a monument planned for the center in the 19th century never got beyond its base.
It was named in 1813 after the Spanish Constitution of Cádiz of 1812, which was sworn here.
Yes, inside the National Palace on the east side of the square; entry is free with an ID.