Cuba

Cuba's two entries were preserved by the same thing: an absence of money to demolish anything. Havana was the assembly point for Spain's treasure fleets and its walls, forts and mansions were built on that traffic; after 1959 there was no capital to replace them, which is why Old Havana survives whole and is also crumbling. Trinidad stopped when Cuban sugar moved west, and nothing significant has been built there for over a century.