This website gives a short history of the demonstration that took place in the Haymarket. It also gives a description of the monument and where it stands. However, there are some very interesting side notes on this page. The first of which is that is explains how this massacre later led to a delegate at a world conference urging the committee that May 1st be remembered as a "labor day" and serve as a tribute to all of those that had to fight for workers rights. The ironic thing about this is that United States was one of the countries that did not sing onto the idea even though the actual event had happened in Chicago. The next interesting fact is that the article claims the monument serves as a "shrine to the Bill of Rights" and especially the right to free speech.
http://www.kentlaw.edu/ilhs/haymkmon.htm
