The Laws of the Indies, codified most fully in Philip II's Royal Ordinances of 1573, set out detailed rules for founding and laying out Spanish colonial towns throughout the Americas. They prescribed a regular grid of streets oriented around a central rectangular plaza, with the church, town hall and main institutions facing the square, and graded the placement of plots outward by status. The ordinances also covered site selection, defence and relations with indigenous populations. They distilled Renaissance ideas of ordered urban design into administrative regulation.
The code became the most extensively executed planning instrument in history, with hundreds of cities from California to Argentina laid out according to its grid-and-plaza template. Its imprint remains visible in the central squares and rectilinear plans of Latin American cities today.