Chhatrapati Shivaji Maharaj Museum is just one of the attractions in Fort, Mumbai so you might want to stop by during your trip. If you want to experience more of the culture Mumbai has to offer, head to Colaba Causeway, Gateway of India, and Mumbai International Cruise Terminal.
If you want to give your credit card some exercise, head out to Colaba Causeway in Colaba. Splash some more cash at Fashion Street Market.