Actually, Valletta is one of those cases where the star fort on the end of that peninsular came first; the city and curtain wall around the city came later (followed by another wall (since demolished) farther inland). The knights of Malta had some of the most advanced castle engineering skills in Europe in their day. That grid pattern of streets was the first in Europe, pre-dating others by 70 years, and the star fort was one of the first built outside of Italy (where the design originated).