Portugal's capital is Lisbon. The official language is Portuguese and the government is a republic. Some of the largest cities include Lisbon, Porto, and Santarém. Christmas and Catholic holidays are important to Portuguese culture. When interacting with Portuguese people, it is polite to greet with a smile, use formal titles, remove hats indoors, and not remove jackets without being asked. Portuguese architecture has been influenced through the centuries by Romans, Moors, Gothic, Manueline, Baroque and modern styles.