El vestíbulo del teatro era pequeño, pero muy elegante.

Because de + el contracts to del in Spanish.

• de el teatro → del teatro
• This is mandatory with el (the masculine singular article), unless El is part of a proper name, such as de El Escorial.

So el vestíbulo del teatro means the lobby of the theatre / the theatre lobby.

Era is the imperfect form of ser, and it is used here to describe a background characteristic or ongoing state in the past.

• era pequeño, pero muy elegante = it was small, but very elegant

A native English speaker often asks why not fue. In general:

• era = describes what something was like, gives background, sets the scene
• fue = presents something as a completed event or fact

Here, the sentence is describing the theatre lobby’s appearance, so era is the natural choice.

Yes. In Spanish, adjectives usually agree with the noun in gender and number.

Here, the noun is el vestíbulo, which is:

• masculine
• singular

So the adjectives must also be masculine singular:

• pequeño
• elegante

Note that elegante does not change between masculine and feminine in the singular:

• el vestíbulo elegante
• la sala elegante

But pequeño does change:

• pequeño (masculine singular)
• pequeña (feminine singular)

Because in Spanish, after a form of ser, adjectives usually come directly after the verb.

So:

• era pequeño
• era muy elegante

This works like English was small / was very elegant. You do not need an article before the adjective.

Muy means very and intensifies the adjective that follows it.

• elegante = elegant
• muy elegante = very elegant

It works like English very, and it usually comes directly before an adjective or adverb.

Yes, pero is the normal word for but when contrasting two ideas.

Here the contrast is:

• pequeño = small
• muy elegante = very elegant

So the sentence means that although the lobby was small, it was also very elegant.

For most everyday cases, pero works just like English but.

Vestíbulo usually means lobby, entrance hall, or foyer, depending on context.

In a theatre, vestíbulo would commonly refer to the lobby or foyer area near the entrance.

A learner may also know hall from English, but Spanish uses different words depending on context:

• vestíbulo = lobby / foyer / entrance hall
• pasillo = corridor / hallway
• salón = large sitting room / hall / lounge, depending on context

So vestíbulo is a fairly specific word here.

Both are grammatically possible, but the original order reflects the speaker’s chosen emphasis.

In pequeño, pero muy elegante, the speaker presents:

1. one quality
2. then a contrasting quality

Putting pequeño first makes the contrast stronger: it was small, but elegant.

Spanish word order is often flexible, but the order chosen can affect what feels most natural or what gets emphasis.

Yes, teatro is a masculine noun:

• el teatro

So when saying of the theatre, you get:

• del teatro

Many Spanish nouns ending in -o are masculine, and teatro follows that common pattern.

The written accent in vestíbulo shows where the stress goes:

• ves-TÍ-bu-lo

Without the accent mark, the stress rules of Spanish would suggest a different pronunciation, so the accent is necessary.

A rough pronunciation for a native English speaker learning Spanish (Spain) could be:

• vestíbulo ≈ ves-TEE-boo-lo

In Spain, the v and b sounds are very similar in normal speech.

Sometimes you may hear hall in Spanish, especially in informal speech or in some regions, but in standard Spanish, especially in a learning context, vestíbulo is the safer and more standard choice.

For Spanish from Spain, vestíbulo or sometimes recibidor depending on the place and context is more clearly Spanish. In a theatre, vestíbulo is very natural.

Because Spanish does not need to repeat the subject once it has already been stated.

The structure is:

• El vestíbulo del teatro = subject
• era = verb
• pequeño, pero muy elegante = description

Once the subject is given, Spanish just continues with the verb and adjectives. Repeating el vestíbulo later would be unnecessary.

That would be possible in English in some contexts, but it is not what the Spanish literally says.

• pequeño = small
• no era grande = wasn’t big

These can be similar in meaning, but they are not exactly the same expression. The Spanish sentence directly uses pequeño, so small is the closest match.