REQUIREMENTS TO APPLY FOR A SHORT STAY, less than 90 days.
US citizens who wish to stay in Spain for tourist or business purposes for up to 90 days do not need a visa. They should travel with a round trip air ticket and a passport valid for a minimum of six months.
The Schengen Agreement establishes a unified type of visa for short stays (up to 90 days) for the participant European countries (Germany, Austria, Belgium, Denmark, Slovakia, Slovenia, Spain, Estonia, Finland, France, Greece, Hungary, Iceland, Italy, Latvia, Lithuania, Luxembourg, Malta, Norway, Netherlands, Poland, Portugal, Czech Republic, Sweden And Switzerland).
Schengen Visa issued by an Embassy or Consulate of the aforementioned countries allows the holder to travel freely in all these countries and it will be issued by the Embassy or Consulate of the country of your main destination, the one where you will spend the longer period of time.