This is one artist's rendering of how Mexico City's Constitution Square, today often called the Zocolo, appeared in May, 1848, toward the end of the American occupation.  This view shows the eastern side of the plaza, as well as portions of the northern and southern sides.  The buildings, from left to right, are: the National Cathedral, the Sagrario, the archbishop's palace and university building; the long National Palace, above which flies the American Flag; and at right, the Municipal Palace.  Beyond the National Palace can be seen the dome, lantern and cross of the Convent of Santa Teresa and the triangular pediment of the Senate. 

On May 29, 1848, after months of negotiations, the news reached Mexico City that terms of peace had been reached by American and Mexican delegations at the nearby town of Guadalupe Hidalgo.  On June 12, as troops of both nations lined up in the main plaza and crowds watched from windows and rooftops, a thirty-gun salute was fired, the American flag was lowered from the National Palace, the Mexican flag was raised in its place, and another salute was fired.  An American band played.  Then Major General William Orlando Butler, who had by this time replaced Winfield Scott, and General William Worth and his division, the rear guard of the American army, marched out of the city.