En la capital, paseamos por una muralla antigua antes de entrar en el barrio viejo.

Here, paseamos means something like we strolled, we walked around, or we went for a walk.

A useful point for learners: with -ar verbs, the nosotros form of the present and the preterite looks the same.

• paseamos = we stroll / we walk around
• paseamos = we strolled / we walked around

So how do you know which one it is? Context. In this sentence, the sequence with antes de entrar makes it sound like a past narration, so the natural reading is we strolled.

The verb pasear often goes with por when you mean moving through, around, or along a place.

• pasear por la ciudad = to stroll around the city
• pasear por el parque = to walk through the park
• pasear por una muralla = to walk along/on a wall

So por is the natural preposition here because it suggests movement within or along that space.

Using en would sound less natural with pasear in this meaning, and a would not fit this idea of wandering around.

Muralla is a city wall, fortified wall, or defensive wall. It usually refers to a large historical structure, often surrounding a town or part of it.

Muro is a more general word for wall.

So:

• muro = any wall
• muralla = a large historic or defensive wall

In this sentence, muralla is used because it suggests an old fortified wall, the kind you might find in a historic capital.

Yes, both can mean old, but they are not always used in exactly the same way.

Antiguo / antigua often fits things that are ancient, historical, or of long standing.

• una muralla antigua = an ancient / old historical wall

Viejo / vieja often means old in the sense of aged, longstanding, or old-fashioned. With places like barrio, it can sound very natural for the old part of town.

• el barrio viejo = the old quarter / old neighborhood

In practice, this pairing sounds idiomatic:

• muralla antigua
• barrio viejo

Also, in Spain, expressions like casco viejo or barrio viejo are very common for historic town centers.

After antes de, Spanish normally uses an infinitive when English might use before entering or sometimes before we entered.

So:

• antes de entrar = before entering / before going in

You cannot say antes de entramos because after the preposition de, Spanish does not use a normal finite verb form like that.

If you want a full clause with a subject, Spanish usually uses:

• antes de que + subjunctive

For example:

• antes de que entráramos en el barrio viejo = before we entered the old quarter

But in your sentence, antes de entrar is simpler and very natural.

In Spain, entrar en is the most natural and standard choice in a sentence like this.

• entrar en el barrio = to enter/go into the neighborhood

You may also hear entrar a or entrar al in other varieties of Spanish, especially in parts of Latin America. Those forms are not necessarily wrong, but for Spanish from Spain, entrar en is especially common.

So if you are learning Peninsular Spanish, entrar en el barrio viejo is a very good model.

The articles help show whether the noun is specific or non-specific.

• la capital: a specific capital, already understood from the context

  • en la capital = in the capital

• una muralla antigua: an old wall, introduced as new information

  • not a specific wall already known to the listener

• el barrio viejo: a specific old quarter/neighborhood

  • often understood as a known part of the city

So the sentence moves from known setting (la capital) to a newly mentioned object (una muralla antigua) and then to another specific place (el barrio viejo).

In Spanish, the normal position for most descriptive adjectives is after the noun.

• una muralla antigua
• el barrio viejo

That is the most straightforward, neutral order.

If you put the adjective before the noun, it often sounds more literary, emotional, or stylistically marked:

• una antigua muralla

This can still mean an ancient wall, but it feels a bit more descriptive or elevated. Also, some adjectives can change meaning depending on position, so for learners, the safest default is:

• noun + adjective

It can mean literally old neighborhood, but in many contexts it suggests the old quarter or historic district of a city.

So in a sentence like this, especially with la capital and una muralla antigua, el barrio viejo probably refers not just to any neighborhood that happens to be old, but to the traditional, older part of the city.

This is a common way Spanish describes historic urban areas.

The comma separates an opening phrase that sets the scene:

• En la capital, ... = In the capital, ...

This kind of fronted location phrase is often followed by a comma in Spanish, especially when the writer wants a slight pause or wants to frame the setting clearly before the main action.

Without the comma, the sentence would still be understandable:

• En la capital paseamos por una muralla antigua...

But the comma makes the sentence feel a bit clearer and more polished in writing.