1896 was an eventful year. It marked the first modern Olympic games in Athens, Greece, as well as the very first time a doctor used radiation as a treatment for breast cancer. It also happens to be the year that the now-iconic Dow Jones Industrial Average (DJINDICES: ^DJI) came into existence.Tomorrow, May 26, will mark the Dow's 122nd birthday -- but since it falls on a Saturday, we're jumping the gun and celebrating a day early. Quite a bit has changed for the stock market's most watched index over the past 122 years.