Learn Italian: La città in cui vivevamo ha molte rovine antiche. - The city in which we used to live has many ancient ruins.

Yes, absolutely! In Italian, the relative adverb dove (where) is very often used instead of in cui (in which) when referring to a physical place. Both are perfectly correct, though dove is a bit more common in everyday spoken Italian.

Why is vivevamo in the imperfect tense while ha is in the present tense?

The tenses reflect different timeframes. vivevamo (we used to live) is in the imperfect because it describes an ongoing state in the past. However, the city still possesses those ruins right now, so ha (has) is in the present tense.

Why is there an 'h' in antiche?

The feminine singular form is antica (ancient), which has a hard 'c' sound like a 'k'. To keep that hard 'c' sound in the feminine plural, you must add an 'h' to make it antiche. Without the 'h', it would be pronounced with a soft 'ch' sound.

Why is it molte and not just molto?

Here, molte (many) is an adjective describing the feminine plural noun rovine (ruins), so it must match in gender and number. You only use the unchanging molto when it acts as an adverb, such as when describing how you do something.