Take Line 4 of the subway (towards Longjiang) and get off at Gulou Station. Transfer within the station and walk 80 meters to board Line 1 (towards Nanjing八卦洲大桥南, which translates to Nanjing八卦ZHOU Bridge South, but for clarity and common usage, it should be "towards Nanjing Yangtze Bridge"). Get off at Hongshan Zoo Station and walk 10 meters to reach Hongshan Zoo.