Auch is an Adverb in this sentence, so it follows the rules for an adverb. In german Adverbien come either at the beginning or in the middle. In the middle they are "more complex", it depends now what other parts are in this sentence. In this sentence we have "in Spanien" and this is an adverbiale Bestimmung des Ortes and Adverbien always come in front of the Präposition of the adverbiale Bestimmung.
So for general placement of Adverbien:
If you put it at the beginning, then its at the beginning, nothing complicated (others might become complicated then).
If you put it in the middle the following are rules/guidelines apply:
The Adverb usually comes in front of the Akkusativobjekt if the Akkusativobjekt is a noun.
The Adverb comes in behind of the Akkusativobjekt if the Akkusativobjekt is a pronoun.
The Adverb usually comes behind the Dativobjekt.
The Adverb comes in front of the Präposition of the Adverbialen Bestimmung.
The Adverb comes at the "end", when theres no Objekt or Adverbiale Bestimmung.
The Adverb's position can differ if you want to put a special emphasis.
Multiple Adverbs usually come in a specific order.
Not all Adverbs tend to be at the same places as some other Adverbs. How you can place an Adverb depending on emphasis differs for several Adverbien.