Ortelius' work is generally considered to be the first modern atlas, marking a break with the Ptolemaic tradition.

When it first appeared it consisted of 53 map sheets. Ortelius added new maps to subsequent editions: there were 119 by the time of his death in 1598.

Citation: Abraham Ortelius, Theatrum Orbis Terrarum (Antwerp, 1571). Marsh's Library Exhibits ‘Mapping History’ curated by Annaleigh Margey, Jason McElligott and Sue Hemmens with Armagh Robinson Library; Held by Marsh's Library (IE-DuMAL); accessed April 30, 2025, https://www.marshlibrary.ie/digi2/exhibits/show/maps/item/417