If in Kolkata and you have a day to spare, and a mood for a long walk, you could try walking around BBD Bagh, formerly called Dalhousie Square. Red colored old buildings, surround you on all sides. The best day would be a Sunday, as most offices in the area are closed and the traffic is minimum. We strolled around for nearly 2.5 hours around the place, resting whenever we felt like by the road. Streets were lined with trees on both sides which was very soothing.