Questo museo è molto popolare.

Because museo is a singular masculine noun, and the demonstrative must agree with it.

• questo = this, for singular masculine nouns
• questa = this, for singular feminine nouns

So:

• questo museo = this museum
• questa casa = this house

In Italian, a demonstrative like questo already does the job of this, so you do not also use the definite article.

So Italian says:

• questo museo = this museum

Not:

• il questo museo ❌

This is similar to English, where you say this museum, not the this museum.

The accent is important because è means is.

Without the accent, e means and.

So:

• è = is
• e = and

That small accent changes the meaning completely.

È is the third-person singular form of essere = to be.

Here are a few forms:

• io sono = I am
• tu sei = you are
• lui/lei è = he/she is

Since questo museo is a singular thing, Italian uses è.

Here molto means very because it is modifying the adjective popolare.

So:

• molto popolare = very popular

Molto can have different roles in Italian depending on how it is used:

• as an adverb: molto interessante = very interesting
• as an adjective/pronoun: molti turisti = many tourists

In this sentence, it is an adverb, so it does not change form.

Popolare is an adjective that ends in -e, and many Italian adjectives of this type use the same singular form for both masculine and feminine.

So you get:

• un museo popolare = a popular museum
• una città popolare = a popular city

The plural changes to -i:

• musei popolari = popular museums
• città popolari = popular cities

So in this sentence, popolare is singular because museo is singular.

Usually, yes, popolare often means popular in the sense of well-liked or well-known.

For example:

• un cantante molto popolare = a very popular singer

But depending on context, popolare can also have other shades of meaning, such as relating to the people, working-class, or folk/traditional in some expressions.

In Questo museo è molto popolare, the normal meaning is simply This museum is very popular.

This is the most neutral and natural word order in Italian:

• subject: Questo museo
• verb: è
• adverb + adjective: molto popolare

Italian can sometimes change word order for emphasis, but this standard order is the one learners should use first.

For example, Molto popolare è questo museo is possible only in a marked, literary, or strongly emphatic style. It is not the normal everyday way to say it.

A simple pronunciation guide is:

KWEH-stoh moo-ZEH-oh eh MOL-toh poh-poh-LAH-reh

A few useful points:

• qu in questo sounds like kw
• z in museo is usually pronounced like dz or a soft ts/dz sound depending on accent
• è is an open eh
• popolare has stress on -la-: popo-LA-re

If you want to sound more natural, try saying it smoothly rather than word by word.

You need to change the demonstrative, the noun, the verb, and the adjective:

• Questo museo è molto popolare.
• Questi musei sono molto popolari.

Changes:

• questo → questi
• museo → musei
• è → sono
• popolare → popolari

Molto stays the same because it is an adverb.

Yes, but it means something slightly different in structure.

• Questo museo è molto popolare = This museum is very popular.
• Questo è un museo molto popolare = This is a very popular museum.

The first directly talks about this museum. The second starts with this is... and then identifies it as a very popular museum.

Both are correct, but they are not exactly the same sentence pattern.