In Portugal, the ability for a 16-year-old to stay in a hotel unsupervised depends primarily on the hotel's individual policy and the possession of a signed parental authorization. Legally, the age of majority in Portugal is 18; however, many hostels and hotel chains (such as Pousadas de Juventude/Youth Hostels) allow those aged 16 and 17 to book and check in alone provided they present a valid "Authorization for Underage Person to Travel" form accompanied by a copy of their parent's or legal guardian's ID. Without this documentation, most reputable hotels will deny entry to minors to comply with child safety and liability regulations. Some international chains, like Meininger, specifically offer "Teens" booking options on their websites for this age group. In contrast, "Adult-Only" hotels or high-end luxury resorts may maintain a strict 18+ policy for the primary guest. It is always mandatory for the 16-year-old to provide their own government-issued ID (passport or national ID card) at reception for mandatory police registration.