The "Book or Bust" Rule (Tickets)

I cannot stress this enough: for the big hitters like La Sagrada Família and Park Güell, you must book your tickets online well in advance. They sell out days (sometimes weeks) ahead.

• Best Time: Aim for the first slot in the early morning to beat the crowds.

• The "Golden Hour" Hack: If you aren't an early bird, book the Sagrada Família for the late afternoon. The sun hits the stained glass windows and the whole interior glows red and orange—it is jaw-dropping.