The name is thought to originate from the time of the Roman occupation, when there was a port here on the River Lena, navigable in those days, in which the millstones (Mós), extracted from a quarry in the region, were loaded and unloaded.
The fact that the Porto de Mós region has been inhabited for thousands of years is very apparent in the Municipal Museum, which contains various fossils and bones of dinosaurs, as well as evidence of human occupation in various periods, such as objects of polished flint stone (Paleolithic and Neolithic), and coins and iron lances from the Roman period.
The castle, built at the highest point in the area, and rebuilt by order of King Dom Sancho I in the 13th century, and two centurys latter, was converted into a fortified palace with a fine and unusual design that has been preserved up to the present day.
In the surrounding area there is the Nature Park of the Serra de Aire and Candeeiros, with its limestone slopes, whose open porous interior contains beautiful underground tunnels that can be visited in grottoes such as those of Santo António, Alvados and Mira d'Aire. On the surface, between traditional villages and quarries, there is evidence of the movement of dinosaurs along the recently discovered trail of the Pedreira da Galinha, and of the Roman occupation, of which the best example is the causeway in Alqueidão da Serra.