Here are the specific excerpts from the Laws of the Indies:
112. The main plaza is to be the starting point for the town; if the town is situated on the sea coast, it should be placed at the landing place of the port, but inland it should be at the center of the town. The plaza should be square or rectangular, in which case it should have at least one and a half its width for length inasmuch as this shape is best for fiestas in which horses are used and for any other fiestas that should be held.
113. The size of the plaza shall be proportioned to the number of inhabitants, taking into consideration the fact that in Indian towns, inasmuch as they are new, the intention is that they will increase, and thus the plaza should be decided upon taking into consideration the growth the town may experience. [The Plaza] shall be not less that two hundred feet wide and three hundred feet long, nor larger than eight hundred feet long and five hundred and thirty feet wide. A good proportion is six hundred feet long and four hundred wide.
114. From the plaza shall begin four principal street: One [shall be] from the middle of each side, and two streets from each corner of the plaza; the four corners of the plaza shall face the four principal winds, because in this manner, the streets running from the plaza will not be exposed to the four principal winds, which would cause much inconvenience.
115. Around the plaza as well as along the four principal streets which begin there, there shall be portals, for these are of considerable convenience to the merchants who generally gather there; the eight streets running from the plaza at the four corners shall open on the plaza without encountering these porticoes, which shall be kept back in order that there may be sidewalks even with the streets and plaza.
116. In cold places, the streets shall be wide and in hot places narrow; but for purposes of defense in areas where there are horses, it would be better if they are wide.
117. The streets shall run from the main plaza in such manner that even if the town increases considerably in size, it shall not result in some inconvenience that will make ugly what needed to be rebuilt, or endanger its defense or comfort.
118. Here and there in the town, smaller plazas of good proportion shall be laid out, where the temples associated with the principal church, the parish churches, and the monasteries can be built, [in] such [manner] that everything may be distributed in a good proportion for the instruction of religion.
119. For the temple of the principal church, parish, or monastery, there shall be assigned specific lots; the first after the streets and plazas have been laid out, and these shall be a complete block so as to avoid having other buildings nearby, unless it were for practical or ornamental reasons.
120. The temple of the cathedral [principal church] where the town is situated on the coast shall be built in part so that it may be seen on going out to sea and in a place where its buildings may serve as a means of defense for the port itself.
121. Next, a site and lot shall be assigned for the royal council and cabildo house and for the custom house and arsenal, near the temple, located in such a manner that in times of need the one may aid the other; the hospital for the poor and those sick of noncontagious diseases shall be built near the temple and its cloister; and the hospital for the sick with contagious diseases shall be built in such a way that no harmful wind blowing through it may cause harm to the rest of the town. If the latter be built in an elevated place, so much the better.
122. The site and building lots for slaughter houses, fisheries, tanneries, and other business which produce filth shall be so placed that the filth can easily be disposed of.
123. It shall be of considerable convenience if those towns that are laid out away from seaports, inland, be built if possible on the shore of a navigable river, and attempts should be made to place the town on the side from which the cold north wind blows and that buildings that cause filth be placed on the side of the river or sea below the town.
124. The temple in inland places shall not be placed on the square but at a distance and shall be separated from any other nearby building, or from adjoining buildings, and ought to be seen from all sides so that it can be decorated better, thus acquiring more authority; efforts should be made that it be somewhat raised from ground level in order that it be approached by steps, and near it, next to the main plaza, the royal council and cabildo and customs houses shall be built. [These shall be built] in a manner that would not embarrass the temple but add to its prestige. The hospital for the poor who are not affected by contagious diseases shall be built near the temple and near its cloister, and the [hospital] for contagious diseases shall be built in an area where the cold north wind blows, but arranged in such a way that it may enjoy the south wind.
125. The same plan shall be observed in any inland place without shore, taking considerable care to ascertain the availability of those conveniences that are required.
126. In the plaza, no lots shall be assigned to private individuals; instead, they shall be used for the buildings of the church and royal houses and for city use, but shops and houses for the merchants should be built first, to which all the settlers of the town shall contribute, and a moderate tax shall be imposed on goods so that these buildings may be built.
The Laws of the Indies became so widespread and durable, it is possible to see the urban arrangement of a main plaza with surrounding church and governmental buildings in former Spanish settlements from the southwestern United States to South America.