Aunque la iglesia era sencilla, mi amiga dijo que la catedral era lo que más quería ver.

Aunque means although / even though. It introduces a contrast.

In this sentence:

Aunque la iglesia era sencilla...
= Although the church was simple...

It sets up a contrast with the second part:

• the church was simple
• but her friend still especially wanted to see the cathedral

Spanish often uses aunque just like English although.

After aunque, Spanish can use either the indicative or the subjunctive, depending on meaning.

Here, era is imperfect indicative because the speaker is treating the information as a real fact:

• Aunque la iglesia era sencilla... = the church really was simple

If the speaker were expressing doubt, concession, or something hypothetical, the subjunctive could appear in other contexts. But here it is a straightforward description of reality, so era is natural.

Era is the imperfect form of ser. It is used here because the sentence is describing a background characteristic of the church:

• la iglesia era sencilla = the church was simple

The imperfect is common for:

• descriptions
• background information
• ongoing states in the past

So era sencilla describes what the church was like, rather than presenting a completed event.

Dijo is the preterite of decir, and it is used because she said is treated as a completed action at a specific moment.

• mi amiga dijo... = my friend said...

If you used decía, it would sound more like:

• she was saying
• she used to say
• she kept saying

Here, the sentence refers to one completed act of speaking, so dijo fits best.

Quería is the imperfect of querer, and here it expresses an ongoing desire or preference in the past:

• lo que más quería ver = what she most wanted to see

Using quería focuses on her desire as a state or feeling.

If you said quiso ver, it would more often suggest she tried / she decided / she wanted and acted, depending on context. In this sentence, the idea is simply her strongest wish, not a completed act of wanting, so quería is the better choice.

Lo que más means something like:

• what ... the most
• the thing that ... most

So:

la catedral era lo que más quería ver
= the cathedral was what she most wanted to see
or more naturally in English:
= the cathedral was the thing she most wanted to see

The structure lo que is very common in Spanish for what / the thing that.

In lo que, the lo is a neuter article. It does not refer to a masculine noun. Instead, it means something like:

• that which
• the thing that
• what

So:

• lo importante = what is important / the important thing
• lo que dijo = what he/she said
• lo que más quería ver = what she most wanted to see

This lo is a very common feature in Spanish and often has no exact one-word equivalent in English.

That era is linking la catedral to lo que más quería ver.

Literally:

• the cathedral was what she most wanted to see

This is a normal ser structure where one thing is being identified as another:

• Madrid es la capital = Madrid is the capital
• Eso es lo mejor = That is the best thing
• La catedral era lo que más quería ver = The cathedral was what she most wanted to see

So the second era is not just repeating the first one randomly; it is the main verb of that clause.

Más is modifying the idea of wanted, not the idea of see.

• lo que más quería ver = what she most wanted to see

This means the cathedral ranked highest among the things she wanted to see.

If you move más elsewhere, the meaning can change or become less natural. Spanish often places más before the verb or structure it intensifies:

• lo que más quería
• el que más me gusta
• lo que más me interesa

So this word order is the natural way to express what she wanted most.

In Spanish, possessives like mi, tu, su, nuestro usually replace the article.

So you say:

• mi amiga = my friend
• not la mi amiga

This is the standard pattern in modern Spanish.

Both can be translated as church, but they are not the same thing.

• iglesia = church, in a general sense
• catedral = cathedral

A catedral is a specific kind of church, usually the principal church of a diocese and the seat of a bishop.

So in the sentence, the contrast is between:

• a simple church
• the cathedral, which was the main thing her friend wanted to see

Because both nouns are grammatically feminine:

• la iglesia
• la catedral

That is why you also get feminine agreement where relevant, such as:

• sencilla to match iglesia

Even though catedral ends in -al, it is still feminine. Grammatical gender in Spanish does not always depend on the ending, so nouns have to be learned individually.

Because sencilla is an adjective agreeing with la iglesia, which is feminine singular.

Agreement in Spanish usually works like this:

• masculine singular: sencillo
• feminine singular: sencilla
• masculine plural: sencillos
• feminine plural: sencillas

So:

• la iglesia era sencilla
• el edificio era sencillo

The sentence as written is fully natural and clear. Spanish often keeps the structure explicit.

You could rephrase it in other ways, for example:

• Aunque la iglesia era sencilla, mi amiga dijo que lo que más quería ver era la catedral.

This version is also very natural and means the same thing. It simply changes the focus:

• original: the cathedral was what she most wanted to see
• rephrased: what she most wanted to see was the cathedral

Both are correct; the original is just one natural way of saying it.