When the first modern Olympic Games debuted in Athens in 1896, women were not allowed to compete; the Games founder, Pierre de Coubertin, said that their inclusion would be "impractical, uninteresting, unaesthetic, and incorrect." Not to mention difficult, given the restrictive clothing of the era — corsets, long, heavy, multi-layered hoop skirts, and long-sleeved shirts with high collars.

However by 1900, despite Coubertin’s hesitance, 22 women out of 997 athletes competed in five sports. Tennis, sailing, croquet, equestrian and golf were open to women, even though only golf and tennis had events for women only.

As women’s hemlines shortened, corsets got the heave-ho and the importance of physical fitness for both genders became increasingly accepted, women were slowly admitted into more sports. Along the way there have been some fascinating milestones. Consider the following:

Charlotte Cooper, Olympic tennis champion British tennis player Charlotte Cooper became the first female tennis champion at the Olympics in 1900. (Photo: Hulton Archive/Getty Images)

1. The United States’ first-ever female gold medalist never knew she won a medal. Margaret Abbott was visiting Paris with her mother during the 1900 Olympics when the duo joined — and won — a nine-hole golf tournament. The event was so disorganized that nobody there realized that it was part of the Games until much later when historians discovered that the event was indeed on the Olympic program. The same year, British tennis player Charlotte Cooper became the first female tennis champion.

2. It took another 24 years for women participants to meet the 100-person mark; in the 1924 Paris Olympics, there were 134 female participants — along with 2,954 men.

3. Women accounted for 13 percent of the athletes at the 1964 Games in Tokyo, 23 percent at the 1984 Games in Los Angeles, and more than 44 percent at the 2012 Games in London.

Larisa Latynina Czech gymnast Vera Caslavska, winner of the gold medal in the individual beam competition, is flanked by silver medalist Tamara Manina (left) and bronze medalist Larisa Latynina, both from the Soviet Union, at the 1964 Olympic Games in Tokyo. (Photo: STF/AFP/Getty Images)

4. Until 2012, Soviet gymnast Larisa Latynina held the record for having won the most medals of any athlete (male or female) in Olympic history. Between 1956 and 1964 she won medals in 18 gymnastics events. When Michael Phelps broke the 48-year record at the London Games, Latynina quipped that it was time for a man to be able to do what a woman had done long ago.

5. When women’s boxing was added to the 2012 London Olympic Games, it was the first time that women had competed in every sport on the Olympic program.

6. However, women’s boxing wasn’t without controversy. International Amateur Boxing Association (AIBA) officials suggested that female boxers should wear skirts to distinguish them from men in the ring. The notion of keeping the ladies in skirts didn’t sit very well with many; in the end it was determined that women could wear "either shorts or the option of a skirt."

7. For the 2012 London Olympic Games, Saudi Arabia, Qatar and Brunei sent female competitors for the first time. Despite that, not all nations included women athletes; Barbados and Nauru had no female participants.

Wojdan Shaherkani Saudi Arabia's Wojdan Shaherkani at the London 2012 Olympic Games. (Photo: Toshifumi Kitamura/AFP/Getty Images)

8. During the 2012 Games, Wodjan Ali Seraj Abdulrahim Shaherkani from Saudi Arabia was almost not allowed to compete in her judo event because the International Judo Federation (IJF) said that for safety reasons, she would not be allowed to wear her hijab. Her father said that if she could not wear the head scarf, she would not compete. Fortunately, the IJF and International Olympic Committee (IOC) came to an agreement and she was allowed to compete wearing her hijab.

9. Since 1998, female ski jumpers have petitioned to join every Winter Olympics and have been denied. While the official word was that there were not enough excellent athletes to ensure a real competition, rumors said otherwise. Gian Franco Kasper, International Ski Federation's (FIS) president and a member of the IOC, said women shouldn’t ski jump because the sport "seems not to be appropriate for ladies from a medical point of view" — that is, it could harm the uterus. Finally, female ski jumping was accepted for inclusion in the 2014 winter games; we don’t expect to see any uteruses falling out of the athletes.

That said, not everyone is convinced women should be ski jumping. Alexander Arefyev, the Russian men's ski jumping coach, told the Izvestia newspaper, "If I had a daughter I would never allow her to jump — it's too much hard work. Women have a different purpose: to raise children, do the housework." To which we'd like to add, "and fly through the air attached to a pair of skis, should they choose to do so."

Simone Manuel celebrates in the pool after winning the gold medal in the women's 100-meter freestyle final at the Rio Olympics. Simone Manuel celebrates in the pool after winning the gold medal in the women's 100-meter freestyle final at the Rio Olympics. (Photo: Adam Pretty/Getty Images)

10. At the Rio Olympics in 2016, Simone Manuel became the first African-American female swimmer to win gold in an individual event when she completed the women's 100-meter freestyle in 52:70, setting an Olympic record. “Coming into the race I tried to take weight of the black community off my shoulders. It’s something I carry with me," Manuel told USA Today. "I want to be an inspiration, but I would like there to be a day when it is not ‘Simone the black swimmer.’"

11. There are only two Olympic sports where men and women are pitted directly against each other: equestrian and sailing.

12. There are only two Olympic sports that have mixed-gender teams: tennis and badminton.

13. And while it’s true that it took until now for women to be included in all sports, there are still two sports in which men are not allowed to compete: synchronized swimming and rhythmic gymnastics.

Synchronized swimmers from Japan perform their free routine at the 2016 Rio Olympics. Synchronized swimmers from Japan perform their free routine at the 2016 Rio Olympics. (Photo: Buda Mendes/Getty Images)