Learn French: C'est un beau château moderne. - It is a beautiful modern castle.

In French, most adjectives go after the noun, which is why we say château moderne. However, a small group of common adjectives describing Beauty, Age, Goodness, and Size go before the noun. Since beau (beautiful) describes beauty, it goes before château.

Can I group the adjectives together and say un beau moderne château?

No, you can't group them like we do in English. Each adjective must follow its own placement rule. Because beau goes before the noun and moderne goes after, they have to "sandwich" the noun, giving us un beau château moderne.

Why is it beau and not bel or belle?

Château is a masculine singular noun that starts with a consonant, so it takes the standard masculine form beau. You would use belle if the noun were feminine, and bel if it were a masculine noun starting with a vowel or a silent H (like un bel hôtel).

Why do we use c'est here instead of il est for "it is"?