What charity was Andrew Carnegie involved in?

Andrew Carnegie, the richest person in the world during 1901, was known for his philanthropy as he supported many charities through financial contributions. Andrew Carnegie believed that wealthy people ought to give their money back to society.  This is known as the "Gospel of Wealth."
Although Carnegie was known to have given various sums of money to charitable causes prior to 1901, after his retirement in 1901 at the age of 66 his charitable contributions became much more numerous.  Perhaps his most notable charitable cause was his founding of the Carnegie Institution in 1902. During this time, Carnegie made a ten million dollar donation to fund research that forwarded science as well as created a pension for teachers.  
Throughout his life, Carnegie was an avid reader, and therefore it makes sense that Carnegie made numerous charitable contributions to reading and education.  Carnegie is known to have donated to the worthy cause of building over 2,000 public libraries.  He also founded the Carnegie Corporation to aid colleges and other educational institutions.  
Another belief of Carnegie's was his commitment to advancing world peace initiatives.  Carnegie created the Carnegie Endowment for International Peace. By 1911, showing his true belief in the "Gospel of Wealth", Carnegie had parted with 90 percent of his fortune as he donated all of this wealth to charity.   
http://www.americaslibrary.gov/aa/carnegie/aa_carnegie_phil_1.html