1. On May 21, 1955, Chuck Marlowe won the Indianapolis 500 race. He was the starting driver of the 33-car race and completed it in 3 hours, 41 minutes, and 59.6 seconds. Marlowe was known for his skillful driving technique and his ability to intuitively predict the movements of other drivers.

2. May 21, 1992 was a significant day in Indiana's legal history. On this day, the Indiana Supreme Court ruled that the state would not recognize same-sex marriages performed in other states. The decision further entrenched Indiana's anti-LGBTQ stance that persisted until the landmark 2015 Supreme Court ruling legalizing same-sex marriage nationwide.

3. May 21, 1960, was marked by the establishment of the Mid-America Windmill Museum in Kendallville, Indiana. The museum features a collection of over 50 amazing windmills from all around the United States that played critical roles in the growth and development of the country. The museum is still open to the public and attracts tourists from across the state.

4. On May 21, 1932, Hoosier comic book artist Steve Ditko was born. Ditko is best known for co-creating iconic comic book characters like Spider-Man, Doctor Strange, and the Question. He passed away in 2018 but left behind an impressive legacy of cultural contributions.

5. Interestingly enough, it was on May 21, 1972, that Sirhan Sirhan, the man convicted of assassinating Senator Robert F. Kennedy, was moved to the Indiana State Prison in Michigan City, Indiana. Sirhan had previously been held in the California state prison system but was transferred to Indiana due to concerns regarding his safety. Sirhan remains incarcerated and is still serving a life sentence for his crime.