The opening ceremony of the 2004 Summer Olympics was held on August 13, 2004 starting at 20:45 EEST (UTC+3) at the Olympic Stadium in Marousi, Greece, a suburb of Athens. As mandated by the Olympic Charter, the proceedings combined the formal and ceremonial opening of this international sporting event, including welcoming speeches, hoisting of the flags and the parade of athletes, with an artistic spectacle to showcase the host nation's culture and history. 72,000 spectators (with nearly 50 world leaders) attended the event, with approximately 15,000 athletes from 202 countries participating in the ceremony as well. It marked the first-ever international broadcast of high-definition television, undertaken by the U.S. media conglomerate NBC Universal and the Japanese broadcaster NHK. The Games were officially opened by President of the Hellenic Republic Konstantinos Stephanopoulos at 23:46 EEST (UTC+3).

Proceedings Countdown and Welcome The opening ceremony began with a 28-second countdown—one second per Olympics held since Athens last hosted the first modern games, paced by the sounds of an amplified heartbeat. At the end of the countdown, fireworks were set off.

Four hundred percussionists performed the zeimbekiko before marching around the edge of the flooded stadium grounds, accompanied by a 50-person strong bouzouki band. The performance was led by two drummers, one inside the stadium and one projected on the stadium screen from the ancient stadium of Olympia, the locale of the Olympic games in antiquity. On screen was Petros Kourtis, with Nikos Hatzidavitidis responding live at the ceremony. A blazing comet, seemingly coming from the ancient stadium of Olympia, lands on the flooded stadium floor drawing the Olympic Rings with its fire. The comet symbolizes the fire of the ancients giving life to the modern Olympic movement, thus bridging the past and the present together. According to Dimitris Papaioannou, the event "was a pageant of traditional Greek culture and history harkening back to its mythological beginnings, and viewed through the progression of Greek art."

Next, a young Greek boy, Michalis Patsatzis, sailed into the stadium on a giant paper boat waving the host nation's flag, symbolizing Greece's maritime tradition and its close connection to the sea. The Hellenic Naval Band then walks into the stadium. The President of the Athens Organizing Committee for the Olympic Games (ATHOC), Gianna Angelopoulos-Daskalaki, and President of the International Olympic Committee Jacques Rogge walk onto the stadium floor. The Band then performs the Presidential fanfare, where President of the Hellenic Republic Konstantinos Stephanopoulos then also arrives on the stadium floor. The three presidents meet the young boy, before Hymn to Liberty, the Greek national anthem was performed a cappella with the raising of the Greek Flag.

Artistic section The segments that followed were divided in two main parts. The first part of the main artistic segment of the opening ceremony was called "Allegory." "Allegory" introduced the main conceptual themes and ideals that are going to be omnipresent throughout the entire opening ceremony, such as the confluence of the past and present, love and passion as the progenitors of history, and humanity's attempt to understand itself. The second part, called the "Clepsydra," or "Hourglass," celebrates the themes introduced in the "Allegory" section through a portrayal of Greek history from the ancient to the modern times.

Allegory The "Allegory" segment begins with a recitation of a verse from Nobel Prize-winning Greek poet George Seferis' poem "Mythistorema 3." As the verse is being recited on the speakers, the spotlights are focused upon a woman clad in a black gown looking out to the water. Holding a marble sculpture head, the woman seems to be entering into a dream. As she looks into the dark water, a centaur appears whose human and animal parts supposedly symbolize the duality of spirit and body. The centaur then walks about and then throws a spear of light into the center of the stadium, from which a giant statue that exemplifies Cycladic art (and thus one of the first depictions of the human form in Greek art) emerges. This Cycladic head also represents one of the first attempts of humanity to understand itself. With the use of lasers, geometrical shapes and other scientific images (such as a stylistic representation of the Solar System) are displayed on the figure's face. The statue then breaks into pieces that float away, and from within it emerges a smaller kouros statue from the Archaic Period of Greek sculpture, which in turn breaks apart to reveal the depiction of man in a sculpture of the classical period, symbolizing the dawn of individuality and extolling human scale, one of the principal themes of the 2004 Olympics. At the end of this sequence, a cube arises from the water, and a man starts slowly balancing himself on the rotating cube while representations of humankind's greatest achievements, contrasted to humanistic representations and images of people of various ethnicities and ages, are projected onto the pieces of broken sculpture, which seem to be floating above the water. This last sequence is meant to symbolize the birth of logical thought, higher learning, and humanity finally making sense of the world in which it lives. After this sequence, the pieces of sculpture descend to the water, meant to symbolize the Greek isles.

Clepsydra

In the next sequence, Eros, the Greek god of love, is introduced flying over a pair of lovers (a man and a woman) frolicking in the pool of water located in the center of the stadium. The young couple along with Eros symbolize the fact that the humanity which creates and shapes history is born out of love and passion. This segment introduces the next part of the ceremony, the "Clepsydra," which highlights the themes of the opening ceremony through a celebration of Greek history. The lovers then lie down in the water, and both fall into a dream state. Throughout the rest of the scenes from history and mythology, Eros flies over the parade, occasionally touching or stepping on the floats moving beneath him, thus reinforcing the theme of love and passion as the source for all history.

The pageantry following the statues and the introduction of Eros continues to portray scenes that show the sequence of Greek civilization through its art. The scenes start with the Minoan civilization. The first float features the iconic image of Minoan civilization: that of the fertility goddess clad in a bodice exposing her breasts and clutching serpents in both hands. The subsequent floats then feature scenes of bull-jumping, dolphins, and other elements that harken back to the images in the frescoes of Phaistos. The scenes then proceed to the more stark art of the Mycenean civilisation, followed by representations of the Classical period. A chariot carrying an actor portraying Alexander the Great introduces images from the Hellenistic period, which in turn are followed by representations of Byzantine art, the Greek War of Independence, and lastly of 20th century elements of Greek culture, such as the popular shadow-theatre figure Karagiozis, who is said to be a humorous and self-deprecating depiction (and parody) of Greek mentality.

At the end of the parade, "Eros" lowered enough to help a pregnant woman remove her outer garment. This last part represents the ceremony coming into full circle: the "Clepsydra" segment began with the image of the Minoan fertility goddess and is now ending with a pregnant woman representing the future of all humanity and history. With belly glowing, the woman moves into the lake of water as the stadium's lights dim and lights underneath the pool of water turn on, thus creating an image of stars in a galaxy. According to Greek myth, the stars of the galaxy were born out of the milk of Hera's fertile breasts. In fact, the name for the Milky Way Galaxy, the home to planet Earth, was born out of this myth. Slowly the stars rise around the woman, and move to form a rapidly rotating DNA double helix, which is the basis for all life on the planet. Humanity's attempt to understand itself, a theme that has been omnipresent throughout the entire ceremony beginning with the Cycladic head, is further reinforced by the representation of the DNA double helix, which symbolizes humanity's latest and most recent attempt to understand itself: the late 20th and early 21st centuries witnessed great advances in the field of genetics with the mapping of the human genome.

Finally, all the characters of the parade begin to walk inside the pool, around its center, mixing the past and the present in a single marching beat of the drums. The confluence of the past and the present is another main theme of the opening ceremony. The music begins a crescendo with choruses, when all of a sudden an olive tree is lifted from the center of the pool—symbolizing goddess Athena's preferred gift by the Greeks—land and food—over Poseidon's gift, the horse—a tool of warfare. At the music's climax, all the characters stop and raise their arms as if worshipping the Tree, which is high above, surrounded also by the fragments of the deconstructed statues who resemble a mount.

Parade of Nations

In order to prepare for the entry of the athletes to the stadium, the giant pool of water that had been constructed on the floor of the stadium had to first be drained. 2,162,000 liters of water were drained from the stadium in a time period of three minutes, providing a dry, hard surface for the athletes to march and gather on.

Typically, Greece leads the Parade of Nations in any Olympics, with the host nation entering the stadium last. However, since Greece was the host nation, they went last, sending only their flag with the weightlifter Pyrros Dimas as the flag bearer into the stadium at the beginning of the parade, and the athletes themselves at the end of it.

The debut position was given to Saint Lucia (Αγία Λουκία in Greek), who led the Parade of Nations into the stadium. As the nations entered in Greek alphabetical order, Zimbabwe (Ζιμπάμπουε in Greek)—which has usually been the penultimate nation, followed only by the host country—appeared in the middle of the parade. Countries such as the United States and Switzerland, which are usually at the rear of the pack, were granted earlier entries as well due to their position in the Greek alphabet.

The entrances of Afghanistan and Iraq were emotional high points of the parade. The nation of Kiribati made its debut Olympic appearance at the 2004 Summer Olympics, and East Timor marched under its own flag for the first time. Serbia and Montenegro appeared at the Olympics under the nation's new name for the first time since the country was officially renamed in 2003, its only time at the Summer Olympics prior to the union's dissolution in 2006 (just after the 2006 Winter Olympics); it had previously been known as Yugoslavia.

Due to the unpopularity of the American-led invasion of Iraq among Greeks, it had been expected by the media that audience members would protest against the war during the entrance of the American delegation into the stadium by booing; however, the Americans did receive a warm welcome, much to the pleasant surprise of US news anchors covering the event as well as NBC Sports anchor Bob Costas. NBC's coverage of the Olympics has been praised, and the company was awarded with six Emmy Awards for its coverage of the Games and technical production. Additionally, NBC televised all 28 sports in the 2004 Games, becoming the first broadcaster to do so.