What should I visit in Nassau, on a cruise?

Question

Our family is going on a cruise in December- Carnival Glory- 7 Days. Our last stop will be in Nassau. My husband and I went last year and went snorkeling. This time we are wanting to explore the city. What are some things we should go see that would be in walking distance of the ship? Both us like historical things, and I have heard something about a native straw market that sounds interesting. Thanks for any suggestions/help