The A23 freeway was initially designed to take advantage of the sections of the IP6 that were built between Torres Novas and Abrantes.
Some stretches of the IP2 between Alcains and Fundão were also used, since the IP2 no longer exists in the old stretch but in conjunction with the A23.
The rest of the section, that is, up to Guarda, were built later, with the main objective of establishing connections between the coast and the country's Beira Interior region.
The last two sections to be inaugurated were between Gardete and Castelo Branco and between Alcaria and Belmonte, in 2003.