What is the only city in Wiltshire?

Excuse me, could you please clarify something for me? I've come across a statement that mentions the only city in Wiltshire, but I'm not entirely sure which one it is referring to. Could you possibly enlighten me on this matter? Is there a specific city in Wiltshire that stands out as the sole urban area within the county's borders? I'd be grateful for any information you could provide.