Michael Phelps is one of the most captivating athletes we've seen in American sports. We should all embrace his Olympic era because we truly have been witnessing something we might never see again. The curtain has dropped on Phelps in London, but here is a look back at how Phelps accumulated his 22 Olympic medals.

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Phelps' first Olympic race forshadowed the incredible swimming career to come. Phelps was understandably jubilant after winning the gold medal in the 400-meter IM final in Athens. Phelps set a world record of 4:08.26.

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As a 19-year-old in the Athens Games, Phelps won the 100 butterfly in an Olympic record time of 51.25 seconds.

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Phelps' affinity for the butterfly became obvious after his gold-medal-winning swim in the 200 butterfly. Phelps captured gold and set an Olympic record time of 1:54.04.

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The 200m IM provided another opportunity for Phelps to shine. He posted a time of 1:57.14 — a time good enough to win him another gold.

Phelps did his part for Team USA, swimming the butterfly leg of the men's 4x100 medley relay heat during the Athens Games. Despite posting the fastest individual butterfly time and automatically earning a spot in the relay finals, Phelps relinquished his spot to veteran Ian Crocker. However, his swim in the relay heat earned him a gold medal when the USA won gold in the relay final.

Phelps had some help winning the gold medal in the 4x200 freestyle relay. He joined Ryan Lochte, Peter Vanderkaay and Klete Keller in bringing home the gold.

Phelps and teammates Jason Lezak, Neil Walker and Ian Crocker (not pictured) finished in third place in the 4x100 freestyle relay, giving Phelps his first bronze medal.

Michael Phelps couldn't handle Australia's Ian Thorpe in the 200 freestyle. Thorpe took gold in the race, but, at 19 years old, Phelps held his own and picked up the bronze. 

The 100 butterfly final in Beijing might be Phelps' greatest gold-medal win. Phelps claimed victory over Serbian swimmer Milorad Cavic by the slimmest of margins — .01. The race was so close, it seemed hard to determine a winner with the naked eye. This victory gave Phelps his seventh gold medal of the games and the opportunity to break Mark Spitz's 1972 record with his next swim.

Phelps kept the show going, winning gold in the 200 butterfly. Phelps beat out perennial rival Laszlo Cseh and turned in a world-record time of 1:52.49 even though his goggles filled with water during the latter half of the race.

Phelps won the 200 freestyle in a world-record time of 1:42.96. This win further separated Phelps from the Olympic field. With this medal, Phelps joined Mark Spitz, Carl Lewis, Paavo Nurmi and Larisa Latynina as the only modern Olympians to win nine gold medals.

Phelps picked up another gold winning the 200 IM with a time of 1:54.23 in the final.

Phelps took no prisoners during the 400 IM in Beijing. Phelps went out fast, winning the race in a time of 4:03:84, a new world record.

In one of the most exciting relay races in history, Phelps and his US teammates captured a gold medal in the 4x100 relay over the heavily favored French. Phelps' quest for eight gold medals in Beijing rested on the shoulders of veteran swimmer Jason Lezak. Lezak, in a clutch anchor leg, swam down Alain Bernard of France and out-touched him for gold at the wall. 

Phelps swam the lead-off leg of the 4x200 freestyle and behind the performances of teammates Ryan Lochte, Ricky Berens and Peter Vanderkaay (not pictured) captured another gold medal.

Michael Phelps captured his historic eighth gold medal in the Beijing Games with the USA's gold medal in the 4x100 medley relay. Phelps passed Mark Spitz for most gold medals won in a single Olympic games.

Michael Phelps became the first male swimmer to successfully defend his Olympic title twice in the same event. Phelps took the 200 IM crown in both Athens and Beijing and followed that up with an historic gold medal in the 200 IM in London.

Unbelievably, Phelps set out to add to his list of accomplishments in the 100 butterfly in London. Having already become the only swimmer to win the same Olympic event three consecutive times, Phelps added to his legacy by also completing the feat in the 100 butterfly.

Michael Phelps looked destined for another gold in the 200m butterfly but, in a reversal of roles for swimming's Superman, Phelps was out-touched at the wall by South Africa's Chad Le Clos. Phelps simply added another silver medal to his trophy case.

Phelps swam the second leg of the 4x100m relay during the London Games. Phelps posted the fastest leg of the relay, but anchor Ryan Lochte was just out-touched at the wall for gold by French swimmer Yannick Agnel. Phelps and the 4x100m relay team settled for silver.

Phelps' relay teammates (from left) Conor Dwyer, Ryan Lochte and Ricky Berens gave Phelps a lead heading into Phelps' first relay anchor swim. Phelps didn't disappoint as he touched the wall first, adding another gold to his medal count.

Phelps capped his London Olympic experience — and likely his career — sharing the gold medal in the 4x100 medley relay with his teammates. With the help of (left to right) Brendan Hansen, Matt Grevers and Nathan Adrian, Phelps' last race in London met his gold standard.