You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Nanjing

Context:
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.

Question:
What happened around the time that Nanjing was designated as the capital?

many structures were built