generate questions: Because it was designated as the national capital, many structures were built around that time. Even today, some of them still remain which are open to tourists.
What was the designation of Nanjing? {sep_token} What happened around the time that Nanjing was designated as the capital? {sep_token} Are any of the structures that were built at that time still around? {sep_token} The structures that still remain are open to whom? {sep_token}