Why should visitors check the rules before crossing the border ?
: Frankfurt Airport : Amsterdam Schiphol Airport : Oslo Airport , Gardermoen : Funchal Airport , Lisbon Portela Airport , Ponta Delgada Airport , Porto Airport : Barcelona El Prat Airport , Madrid - Barajas Airport ( Also for holders of a Spanish identity card ) : Zürich Airport Sometimes , external border controls are located on non-Schengen territory , but inside the EU .