The period separating two Olympic celebrations, called an olympiad, was the reference as a matter of date in the ancient times. Every event was dated with regards to the olympiads. It was therefore evident for Pierre de Fredy, Baron de Coubertin, to adopt this periodicity for the celebration of the modern Games.
Initially Pierre de Coubertin wished the first Games to take place in Paris. On the request of Vikelas, the first President of the International Olympic Committee, in honor of the ancient Games, the city of Athens was chosen to organize the first Olympic Games of the modern era from March 25 to April 5, 1896 (Julien calendar); Paris was chosen for the second Games in 1900 and so on.
You will now find as many programs as I have up to now, summer as well as winter. And of course this page will be updated each time I will get new information.
Feel free to ask any questions I will be glad to answer.