It's not incorrect, it's just slang. Physiologically it'd be easier to say you're into visiting old towns; Jura gave good examples to how to elaborate on the reasons why you're into doing that. :-)

Hello Lisa_08, "Being into something" refers informally to one's interest. " I am into ......"

Hi, it might be easier to say, 'one of my hobbies is visiting old towns in France/ Europe and then say why. For example are you interested in architecture, the town square, churches, bridges, ancient buildings, cobblestones, cemeteries etc.