Xuanwu Lake is a great place to visit in the fall.

First of all, it's free, so you can visit at any time without having to get up early. Secondly, it's easy to get to. You can take the subway to any of the gates, or even get off at Nanjing Station and walk across the street. You can see the maple leaves of Qixia Mountain, the ginkgo trees of Pilu Temple, and the bald cypress trees of Ming Xiaoling Mausoleum. You can also go birdwatching and watch the sunset.