Learn Spanish (Latin America): El viaje al castillo fue inolvidable. - The trip to the castle was unforgettable.

Context is your best friend! If it meant went, it would usually be followed by a destination. Here, it is followed by the adjective inolvidable (unforgettable), which describes the trip. Because it links the subject to a description, it comes from ser and means was.

Why do we use fue (from ser) instead of estuvo (from estar) to say was?

We use ser to describe the fundamental characteristics of a person, thing, or event. Saying the trip was unforgettable is a lasting, core description of that specific event, so we use fue rather than estuvo.

What exactly is al short for?

The word al is a mandatory contraction of the preposition a (to) and the masculine article el (the). In Spanish, whenever a is followed directly by el, they must merge into al.

The word inolvidable looks quite long. How is it built?

You can break it down into familiar parts! It starts with the negative prefix in- (un- or not), uses the root of the verb olvidar (to forget), and ends with the suffix -able (-able). Put together, it matches English perfectly: un-forgett-able.

The word viaje ends in an e. Is there a rule to remember that it is masculine (el viaje)?

Yes! As a general rule, Spanish nouns that end in -aje are masculine. This is a very handy pattern to learn, as it also applies to common words like el mensaje (the message) and el paisaje (the landscape).