Desde el mirador, vimos un faro al fondo.

Here desde means from in the sense of a starting point or viewpoint: Desde el mirador = From the lookout / viewing point.

It is different from de, which often means of, from, or about, but usually in a broader or less directional way.

• desde el mirador = from the lookout point
• de el mirador would not work here

So if you want to express the place from which someone saw something, desde is the natural choice.

A mirador is a viewpoint, lookout point, or scenic overlook — a place where you go to look out over a landscape, town, sea, etc.

In Spain, mirador is a very common word for:

• a scenic viewpoint in the mountains
• a terrace or balcony with a view
• an official lookout point for tourists

So el mirador in this sentence suggests a place with a wide view.

Vimos is the preterite of ver (to see) for we: we saw.

Spanish uses the preterite here because the sentence describes a completed event:

• Desde el mirador, vimos un faro al fondo.
• From the lookout, we saw a lighthouse in the distance.

If you used veíamos, that would be the imperfect, which usually suggests an ongoing, repeated, or background action:

• Desde el mirador, veíamos el faro cada tarde.
• From the lookout, we used to see the lighthouse every afternoon.

So:

• vimos = we saw, one completed moment/event
• veíamos = we were seeing / used to see

Spanish often leaves out subject pronouns because the verb ending already shows who the subject is.

• vimos already means we saw
• so nosotros vimos is usually unnecessary unless you want emphasis or contrast

For example:

• Vimos un faro. = We saw a lighthouse.
• Nosotros vimos un faro, pero ellos no. = We saw a lighthouse, but they didn’t.

Omitting the pronoun is normal and natural.

Un faro means a lighthouse, so it introduces the lighthouse as something not previously identified for the listener.

Use un when the thing is:

• new information
• not specific to the listener yet
• one example of that kind of object

Use el faro if the lighthouse is already known or specific:

• Vimos el faro que nos habían recomendado.
• We saw the lighthouse they had recommended to us.

So un faro is natural if you are simply mentioning that you saw a lighthouse.

Al fondo means something like:

• in the background
• in the distance
• far back

In this sentence, it suggests the lighthouse was visible far away, probably at the back of the view.

This expression can be used both literally and spatially:

• Hay una puerta al fondo del pasillo. = There’s a door at the end/back of the corridor.
• Se ven montañas al fondo. = You can see mountains in the distance.

Here un faro al fondo means the lighthouse appeared far away in the scene.

Because al = a + el.

The noun is fondo, and in this expression Spanish uses the article:

• al fondo = at/in the back, in the distance

By contrast, a fondo is a completely different expression meaning:

• thoroughly
• in depth
• sometimes full throttle, depending on context

Examples:

• Estudié el tema a fondo. = I studied the topic thoroughly.
• Vimos un faro al fondo. = We saw a lighthouse in the distance.

So al fondo is the correct phrase here.

In Spanish, a + el normally contracts to al.

• a + el fondo → al fondo
• a + el mirador → al mirador

This contraction is mandatory in normal Spanish, except when el is part of a proper name:

• Voy a El Escorial. = I’m going to El Escorial. Not al Escorial in that case.

So al fondo is simply the standard contraction.

Yes. Al fondo is describing un faro.

So the structure is:

• Desde el mirador = from the viewpoint
• vimos = we saw
• un faro al fondo = a lighthouse in the distance / at the back

It works like a noun phrase with extra location information attached:

• un faro = a lighthouse
• un faro al fondo = a lighthouse in the distance

Yes, but the original order is very natural.

Standard order:

• Desde el mirador, vimos un faro al fondo.

Possible alternatives:

• Vimos un faro al fondo desde el mirador.
• Al fondo vimos un faro desde el mirador.

These alternatives are grammatically possible, but they may shift emphasis:

• starting with Desde el mirador highlights the viewing position
• starting with Al fondo highlights where the lighthouse appeared

The original sentence sounds balanced and natural in everyday Spanish.

Usually here it means far away in the view, not necessarily physically hidden behind something.

For a visual scene, al fondo often corresponds to:

• in the background
• in the distance

So from the lookout, the speakers saw a lighthouse that was far off in the landscape or seascape.

If Spanish wanted to say behind something more directly, it would normally use expressions like:

• detrás de
• al otro lado de

So in this sentence, al fondo is mainly about distance and visual depth.

Yes, faro is masculine: el faro, un faro.

Many Spanish nouns ending in -o are masculine, though there are exceptions. In this case:

• singular: el faro
• plural: los faros

That is why the sentence says un faro, not una faro.

A natural English version could be:

• From the lookout, we saw a lighthouse in the distance.
• From the viewpoint, we could see a lighthouse far off.
• From the scenic overlook, we saw a lighthouse in the background.

The closest choice depends on context:

• mirador → viewpoint / lookout / scenic overlook
• al fondo → in the distance / in the background

So while the basic meaning may already be clear, the most natural English wording is often From the lookout, we saw a lighthouse in the distance.