Photos that show how Olympic medals have changed over the last 120 years

American swimmer Michael Phelps is the most-decorated Olympian of all time, as he's won a record 25 medals. Not all of these medals look the same, however. Phelps swam in the 2004, 2008, 2012, and 2016 games, and the design for the hardware was different for each Olympics.

In fact, Olympic medals look different for each Olympiad, reflecting the design influences of the time and the host country. Though there are some motifs that keep reappearing - including a decades-long stretch where the design remained consistent - medals from the Rio Games look very different from the prizes handed out to winners at the 1986 Games.

Here's what the medals looked like at every Summer Olympic Games of the modern era. The photographs come courtesy of the IOC.