Learn French: Tous les bâtiments de la ville sont modernes. - All the buildings in the city are modern.

In French, the word for "all" must match the gender and number of the noun it describes. Because bâtiments (buildings) is a masculine plural noun, we use the masculine plural form tous. Notice that it is placed directly before the definite article les.

Is the 's' at the end of tous pronounced in this sentence?

No, the 's' is silent here. When tous is used as an adjective modifying a noun (like in tous les bâtiments), it is pronounced "too". You only pronounce the 's' when tous is used on its own as a pronoun meaning "everyone" or "all of them".

The English translation says "in the city", so why does the French use de la instead of dans la?

While dans means "in" or "inside", French often uses de (of) to show belonging or association. Literally, this sentence says "all the buildings of the city". Using de is a very natural and common way to link a noun to its location in French.

Why does the adjective modernes have an 'e' before the 's'?

The base singular form of the French adjective for "modern" is moderne. Because adjectives must agree in number with the plural noun les bâtiments, you simply add an 's' to the existing singular word, making it modernes.