A "public place, "public grounds, or "commons" are things or resources generally held by a community or municipality as a body. They are things under the public law (jus publicum) and not jus privati (private.) A public place may be used by any of the civil community's members in common with other members, subject to regulation of that use (under governmental "police powers.") A public place or thing, (such as a city wall), itself, is reserved from private appropriation by any individual.

In the case of Mayor, Aldermen and Inhabitants of New Orleans v. U.S., 35 U.S. 662 (1836), Justice McLean cites European authorities in explanation of the types of property held in common as "public":

"Domat, liv. 1, title 8, sec. 1, art. 1, says, there are two kinds of things destined to the common use of men, and of which every one has the enjoyment. The first are those which are so by nature; as rivers, the sea and its shores. The second, which derive their character from the destination given them by man; such as streets, highways, churches, markethouses, courthouses, and other public places; and it belongs to those in whom the power of making laws and regulations in such matters is vested, to select and mark out the places which are to serve the public for these different purposes..."

"Domat says, 'rivers, their banks, highways, are public places which are for the use of all, according to the laws of the country. They belong to no individual and are out of commerce; the king only regulates the use of them.' And again, in vol. 2, lib. 1, tit. 8, sect. 2, 3 and 16: 'we class public places, as out of commerce; those which are for the use of the inhabitants of a city, or other place, and in which no individual can have any right of property, as the walls, ditches or gates of a city, and public squares.'"

"The 9th law, tit. 20, of Partida 3, [Spanish Law] contains the following: 'the things which belong separately or (severally) to the commons of cities or towns are fountains of water, the places where the fairs or markets are held, or where the city council meet, the alluvions or sand deposits on the banks of rivers, and all the other uncultivated lands immediately contiguous to the said cities, and the race grounds, and the forests and pastures, and all such other places which are established for the common use.'" [Emphasis mine.]

Although such places are commonly formally dedicated on municipal maps for such use, Justice McLean cites two American cases where a "common" was established through longstanding public use as sufficient evidence of a dedication:

"It is not essential that this right of use should be vested in a corporate body; it may exist in the public, and have no other limitation than the wants of the community at large.

"This court had occasion to consider this doctrine in two important and leading cases, which lately came before them, and which are reported in 6 Peters. The first one was the City of Cincinnati v. The Lessee of White."...

The second was the case of Barclay and others v. Howell's Lessee. This case involved the extension of Water Street to the Monongahela river by continued public use, without formal dedication. "[A]nd as the public for thirty years or more, in some parts of the town, had thus used the street; and that property had been bought and sold in reference to it, in this form: it was held to be sufficient evidence of its having been dedicated to the public."

Justice McLean also addresses the prohibition from private appropriation of "public" ground:

"The 23d law, tit. 32, of Partida 3, is as follows: 'no one ought to erect a house or other building or works in the squares, nor on the commons, (exidos) nor in the roads which belong to the commons of cities, towns or other places; for as these things are left for the advantage or convenience and the common use of all, no one ought to take possession of them, or do, or erect any works there for his own particular benefit; and if any one contravenes this law, that which he does there must be pulled down and destroyed; and if the corporation of the place where the works are constructed choose to retain them for their own use, and not pull them down, they may do so; and they make use of the revenue they derive therefrom in the same manner as any other revenues they possess; and we moreover say, that no man who has erected works in any of the above-mentioned places can or shall acquire a right thereto by prescription.'"