Conversation so far:
what happened to andrew carnegie in 1901?
Carnegie invested $40,000 in Story Farm on Oil Creek in Venango County, Pennsylvania.
In one year, the farm yielded over $1,000,000 in cash dividends.
what else happened in a year?
Carnegie worked with others in establishing a steel rolling mill, and steel production and control of industry became the source of his fortune.
was this a success?
I propose to take an income no greater than $50,000 per annum! Beyond this I need ever earn, make no effort to increase my fortune.
what else before?
Carnegie believed in using his fortune for others and doing more than making money.
what did he do?
Carnegie worked to develop several iron works, eventually forming the Keystone Bridge Works and the Union Ironworks, in Pittsburgh.

Question: what was his greatest accomplishment?
Self-contained rewrite: what was Andrew Carnegie's greatest accomplishment?