From the days of the Ming dynasty to the modern age, Nanjing has been the site of some of China's most momentous historical happenings. One of the most important in modern times is commemorated at the Nanjing Massacre Memorial Hall. The site remembers the approximately 300,000 people who lost their lives during WWII. Although a grisly reminder of the toll of war, the museum provides an excellent summary of the events leading up to - and after - the occupation. It's informative and well worth your time, especially as the site is so close to your apartment hotel in Nanjing's Jianye district.
Another must-see historical note to Nanjing is the old city walls, located only a short drive from your serviced apartments. Dating back to the very start of the Ming dynasty, the walls took over 200,000 workers and 21-years to complete. The best time to see the walls is in the morning as during summer the heat can be intense late in the day, and in the winter mornings, mists roll in and give the place a magical feel.