This thesis investigates the evolution of the main square (Z&ograve / calo) in M&egrave / xico City, Mexico, from pre-colonial times to the present in terms of its spatial characteristics and public life. This thesis introduces wide-ranging information about Pre-hispanic America, mainly Aztecs and their urban culture / Spaniards, their background in Europe, and their colonial urban culture in America / and the culture of the Mexican Revolution. After 1810, the &amp / #8216 / independence soul&amp / #8217 / created a nation of so-called &amp / #8216 / cosmic race&amp / #8217 / , whose aspirations were concretized through new political and social transformation of the main square. The new naming of the square as Plaza de la Constitucion and the demolition of the P&agrave / rian introduced this new concept. Even though later social and political developments changed the main character of the square, colonial urban texture still exists. Z&ograve / calo faced major modifications in its eventful history, but still demonstrates the traces of the transformation from Aztec Great Sacred Center, first to colonial town square (Plaza Mayor), second to the national square (Plaza de la Constitucion), and finally to the public arena (Z&ograve / calo).