Visitamos la prisión ayer.

Because visitamos can be either:

• present tense: we visit
• preterite (simple past): we visited

For -ar verbs, the nosotros form is the same in both tenses.

What tells you it is past here is ayer = yesterday. So:

• Visitamos la prisión ayer = We visited the prison yesterday

Without a time word, the form by itself could be ambiguous.

The ending -amos shows first person plural: we.

The verb comes from visitar = to visit.

So:

• visito = I visit / I visited
• visitas = you visit
• visita = he/she visits
• visitamos = we visit / we visited
• visitáis = you all visit (Spain)
• visitan = they visit

In this sentence, visitamos means we visited because of ayer.

Spanish often uses the definite article more naturally than English does.

Here, la prisión means the prison. It suggests a specific prison, or at least treats it as a concrete place being visited.

Also, Spanish often distinguishes between:

• ir a prisión = to go to prison (institutional sense: become imprisoned)
• visitar la prisión = to visit the prison (the actual place/building)

So the article la sounds very natural here.

Because la prisión is the direct object, and with places or things Spanish normally does not use the personal a.

So:

• Visitamos la prisión = correct

But with a person, you usually would use personal a:

• Visitamos a nuestra abuela = We visited our grandmother

So the difference is:

• thing/place → usually no a
• person → usually a

Yes. Ayer is an adverb of time, and Spanish word order is fairly flexible.

All of these are possible:

• Visitamos la prisión ayer
• Ayer visitamos la prisión

Both are correct. The version with ayer at the end is very natural and neutral. Putting ayer first gives a little more emphasis to the time.

Because the stress falls on the last syllable: pri-SIÓN.

Spanish spelling rules say that words ending in n, s, or a vowel are normally stressed on the second-to-last syllable unless there is a written accent.

Since prisión ends in n but is stressed on the last syllable, it needs the accent mark:

• prisión

That accent tells you where to stress the word.

Both can mean prison or jail, and both are understood in Spain.

Very generally:

• prisión can sound a bit more formal or institutional
• cárcel is very common in everyday speech

In many contexts they overlap. A learner should recognize both.

The preterite is used for a completed action, and ayer often points to a finished event in the past.

So:

• Visitamos la prisión ayer = We visited the prison yesterday (completed event)

If you used the imperfect:

• Visitábamos la prisión...

that would usually suggest something habitual, repeated, descriptive, or ongoing in the past, which does not fit this sentence as naturally.

Not naturally. Visitamos is not the form for were visiting.

To express an ongoing action in the past, Spanish would usually use:

• Estábamos visitando la prisión ayer
• or, depending on context, Visitábamos la prisión

But the given sentence most naturally means:

• We visited the prison yesterday

A simple pronunciation guide is:

• bee-see-TA-mos la pree-see-ON ah-YER

More accurately:

• Visitamos → stress on ta
• prisión → stress on sión
• ayer → stress on the second syllable: yer

In Spain, many speakers pronounce c before i like the th in thin, but here there is no c in prisión, so that does not affect this sentence.

Not exactly.

• Visitamos la prisión ayer = We visited the prison yesterday
• Fuimos a la prisión ayer = We went to the prison yesterday

The first focuses on the action of visiting.
The second focuses on going there.

Sometimes both could fit the same real-life situation, but they are not identical in meaning.

The main change would often be the personal a.

Compare:

• Visitamos la prisión ayer = we visited the prison
• Visitamos a Juan ayer = we visited Juan

So with a person, Spanish usually adds a before the direct object. The verb visitar itself still works the same way.