1 WTC 1973 and 2013

http://www.skyscrapercity.com/showthread.php?t=419362&page=1957

http://en.wikipedia.org/wiki/One_World_Trade_Center, http://onewtc.com,
http://ca.news.yahoo.com/last-pieces-1-world-trade-center-rising-skyscraper-064129435.html,
http://www.wtc.com/media/images/s/wtc-construction-1-world-trade-center

http://www.flickr.com/photos/crim/7638329258/

http://www.skyscrapercity.com/showthread.php?p=84125976,
http://www.skyscrapercity.com/showthread.php?t=419362&page=1224,
http://www.skyscrapercity.com/showthread.php?t=419362&page=1280

http://www.theconstructionindex.co.uk/news/view/world-sees-slow-down-in-completions-of-200m-plus-towers

http://en.wikipedia.org/wiki/Antoni_Gaud%C3%AD#Quest_for_a_new_architectural_language,  http://www.skyscrapercity.com/showthread.php?t=419362&page=2104,
http://www.biography.com/people/antoni-gaud%C3%AD-40695