Public domain works must be out of copyright in both the United States and in the source country of the work in order to be hosted on the Commons. If the work is not a U.S. work, the file must have an additional copyright tag indicating the copyright status in the source country.
Note: This tag should not be used for sound recordings.PD-1923Public domain in the United States//commons.wikimedia.org/wiki/File:Planta_do_Teatro_D._Afonso_Henriques.jpg

For background information, see the explanations on Non-U.S. copyrights.
As of 1 January 1996, the following were in the public domain in Portugal: works whose author died before 1946; anonymous works, works deemed to be anonymous, or works by a collective person whose authors were not individually identified, first published or disclosed before 1946; photographic works, works deemed to be photographic works or works of applied art created before 1 July 1970; news articles or economic, political or religious articles, published or disclosed before 1996, provided that rights have not been specifically reserved and mentions, wherever possible, the name of the author and of the publisher, of the title of the work and other elements enabling it to be identified.