You will need a current passport to enter in Europe (or just your identification if you are a European citizen).
For United States and Canada: No visa is required to visit Spain .
Participants from other countries: Please check with the Spanish Embassy or Consulate in your country. Spain is a member of the Schengen Treaty and a single visa will cover entry into a number of European countries.
Check with your doctor to see what shots you might want to consider. None are required and Spain is generally a safe place to visit.