The UN designates the first Monday of October every year, this year being October 3, as World Habitat Day.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/future-urban-habitat
[2] http://admin.indiaenvironmentportal.org.in/category/author/kala-seetharam-sridhar
[3] http://admin.indiaenvironmentportal.org.in/category/newspaper/economic-times-new-delhi
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/habitat-and-urbanisation
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/india
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/development
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/green-house-gases
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/climate-change
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/south-asia
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/energy