Ya sea desde la torre o desde el mirador, la catedral se ve preciosa al atardecer.

It means whether ... or ... / be it ... or ....

So:

• Ya sea desde la torre o desde el mirador... = Whether from the tower or from the viewpoint...

This structure is very common in Spanish when giving two alternatives.

A useful pattern is:

• Ya sea X o Y = Whether X or Y

For example:

• Ya sea en verano o en invierno, hace viento.
• Ya sea por tren o por coche, llegaremos.

It sounds a bit more formal or polished than just listing two options.

Sea is the present subjunctive form of ser.

In the fixed expression ya sea ... o ..., Spanish normally uses the subjunctive because it presents alternatives rather than stating a simple fact.

So you should learn ya sea ... o ... as a set phrase:

• ya sea A o B
• ya sea con amigos o en familia
• ya sea hoy o mañana

You usually would not say ya es ... o ... in this structure.

Spanish often repeats the preposition for clarity and balance, especially in paired structures like this.

So:

• desde la torre o desde el mirador

sounds very natural and symmetrical.

Could you sometimes omit the second desde? In some contexts, yes:

• desde la torre o el mirador

might be understood, but it is less neat here and may sound less natural. Repeating desde makes it clearer that both places are separate viewing points.

• Torre = tower
• Mirador = viewpoint / lookout / viewing platform

A torre is an actual tower structure.

A mirador is a place designed or known for the view. It could be:

• a scenic lookout,
• a balcony-like platform,
• or a high point where people go to admire the scenery.

So the sentence contrasts two places from which you can look at the cathedral.

Because verse here means to look, to appear, or to be seen as.

So:

• La catedral es preciosa = The cathedral is beautiful
• La catedral se ve preciosa = The cathedral looks beautiful

The second one focuses more on how it appears from a certain viewpoint or in certain light, which fits perfectly with desde la torre o desde el mirador and al atardecer.

In other words:

• es preciosa = a general quality
• se ve preciosa = how it looks in that moment / from that angle

Not in the usual English sense of reflexive.

This is the verb verse, which often means:

• to look
• to appear
• to seem visually

Examples:

• Te ves cansado. = You look tired.
• La ciudad se ve preciosa de noche. = The city looks beautiful at night.

So in this sentence, se ve is best understood as part of the verb verse, not as a literal reflexive idea like the cathedral sees itself.

Because preciosa agrees with la catedral, which is:

• feminine
• singular

So the adjective must also be feminine singular:

• la catedral preciosa
• la catedral se ve preciosa

Compare:

• el edificio se ve precioso
• la iglesia se ve preciosa
• los edificios se ven preciosos
• las iglesias se ven preciosas

This is standard adjective agreement in Spanish.

Al atardecer literally comes from:

• a + el atardecer → al atardecer

It means:

• at sunset
• towards evening
• at dusk

This structure al + infinitive can sometimes mean when or upon doing something, but here atardecer is functioning as a noun-like form referring to the time of day.

So you can think of it simply as a time expression:

• al amanecer = at dawn
• al mediodía = at midday
• al atardecer = at sunset / in the evening light

Yes, but the meaning changes a bit.

• por la tarde = in the afternoon
• al atardecer = at sunset / as evening falls
• al anochecer = at nightfall / as it gets dark

So al atardecer is more specific and more picturesque. It suggests that warm sunset light is making the cathedral look especially beautiful.

That makes it a very natural choice in this sentence.

Yes. Spanish allows some flexibility.

For example, you could also say:

• La catedral se ve preciosa al atardecer, ya sea desde la torre o desde el mirador.

This means the same thing, but the emphasis changes a little.

The original sentence starts with the viewing options:

• Ya sea desde la torre o desde el mirador...

That puts the focus first on from where you are looking.

The alternative version starts with:

• La catedral se ve preciosa...

That puts the focus first on the cathedral and how it looks.

Both are correct.

Not always. A very literal translation can sound stiff in English.

Depending on context, ya sea ... o ... may be best translated as:

• whether ... or ...
• be it ... or ...
• either ... or ... (sometimes, though this is not always exact)

In this sentence, the most natural English choice is usually:

• Whether from the tower or from the viewpoint, the cathedral looks gorgeous at sunset.

So it is better to learn the function of the expression rather than forcing one fixed word-for-word translation every time.