Learn Italian: Guardo la città dal tetto. - I look at the city from the roof.

In Italian, when the preposition da (from) is followed by a definite article like il (the), they combine into one single word. Since tetto (roof) is a masculine singular noun starting with a single consonant, it uses the article il. When you combine da + il, they merge to form the articulated preposition dal.

The English translation says "I look at", but I don't see a word for "at" in the Italian sentence. Why?

The Italian verb guardare already means "to look at" or "to watch." Unlike English, Italian doesn't require an extra preposition here. You just connect the verb directly to the thing you are looking at: guardo la città.

How do I know dal means "from the" here? Doesn't da sometimes mean "by" or "since"?

You have to rely on the context! While da can mean "by" or "since" in other situations, it is the primary preposition used to express origin or a physical starting point. Since you are looking outwards from a physical location (il tetto), da means "from".

Why does città have an accent mark on the last letter?