Amenhotep III was born into the Eighteenth Dynasty, the golden age of the New Kingdom, around 1401 BCE. His father was Thutmose IV, the pharaoh who had cleared the sand from the Great Sphinx at Giza after the monument spoke to him in a dream and promised him the throne. His mother was Mutemwiya, a minor wife of Thutmose IV who was never granted the title of Great Royal Wife but whose son would eclipse every queen who had come before him. Amenhotep ascended the throne while still a boy, probably no older than twelve, and may have ruled under a regent during his early years. But the gods, at least in the official story, had already chosen him before his birth.

The defining myth of his legitimacy was carved in the Birth Room of Luxor Temple, a chamber that Amenhotep himself commissioned as part of the vast temple complex he built at Thebes. The reliefs tell the story scene by scene. The god Khnum, the ram-headed creator who moulded mankind on his potter's wheel, fashions two tiny figures - one of the infant Amenhotep and one of his ka, the life force that distinguishes the living from the dead. The goddess Isis watches. Then Amun, the king of the gods, falls in love with Queen Mutemwiya and, disguised as her husband Thutmose IV, enters her chamber. Thoth, the ibis-headed god of wisdom, leads him there. Amun and the queen sit together upon the symbol of heaven, supported by the goddesses Selket and Neith, and Amun puts the breath of life into her nostrils. Before he leaves, he reveals his divinity and tells her the child shall be named Amenhotep, meaning "Amun is satisfied." The queen is led to the birth chamber by Khnum and Hathor, where she delivers the child while seated upon a throne. Thoth announces the birth. The infant is suckled by goddesses, including the nine Hathors, the fairy godmothers of Egypt who decree the fate of every child. The final scene shows him grown, a pharaoh blessed by every god in the pantheon. The message was unmistakable: Amenhotep III was not merely the son of a king. He was the son of a god.

His marriage to Tiye was the most remarkable partnership in Egyptian royal history. Tiye was not a princess. She was a commoner, the daughter of Yuya and Tjuyu, a wealthy couple from the provincial town of Akhmim whose burials in the Valley of the Kings would prove they had risen to the highest circles of power. For a pharaoh to marry outside the royal family was almost unheard of, and to elevate a commoner to Great Royal Wife was revolutionary. Yet Amenhotep did exactly that, and the evidence of their genuine partnership survives in stone. On colossal statues and temple reliefs, Tiye appears at the same scale as her husband, a visual equality that no previous queen had enjoyed. He built her a pleasure lake at T'aru, and the two of them sailed upon it in a boat called the Disk of Beauties. She bore him at least six children: the crown prince Thutmose, who died young; Sitamun, Henuttaneb, Iset, Nebetah, and Beketaten, their daughters; and Amenhotep IV, the second son who would later change his name to Akhenaten and overturn the religion of his fathers. Tiye outlived her husband and remained a power behind the throne during the early years of her son's reign, so formidable that Tushratta, the king of Mitanni, wrote to her directly when her son failed to send the gold he had promised.

The Amarna Letters, a cache of 382 clay tablets discovered in 1887 at the ruined city of Akhetaten, preserve the voice of Amenhotep III's diplomacy. Written in Akkadian cuneiform, the lingua franca of the age, they record correspondence between the pharaoh and the kings of the Great Powers Club: Babylon, Assyria, Mitanni, the Hittites, and Alashiya (Cyprus). The letters reveal a world of elaborate etiquette and barely concealed greed. Tushratta of Mitanni, whose empire was harried by the rising Hittites to his north, calls Amenhotep "brother" and "son-in-law," for he had married Tushratta's daughter Kelu-Heba. In Letter 19, Tushratta professes brotherly love and then begs for gold: "May my brother send to me very much gold that has not been worked. And in the land of my brother gold is plentiful like dirt." In Letter 5, Amenhotep himself writes to Kadashman-Enlil I of Babylon, discussing marriage to the Babylonian king's daughter and dispatching costly gifts. But the pharaohs of Egypt never gave their own daughters in marriage, a rule so absolute that Kadashman-Enlil complains in Letter 4: "Since earliest times no daughter of the king of Egypt has ever been given in marriage." Egypt's supremacy was taken for granted, and Amenhotep's reign was the period when that supremacy was at its peak.

Amenhotep III built on a scale that dwarfed every predecessor. His mortuary temple on the west bank of the Nile at Thebes was the largest temple complex ever constructed in Egypt, covering thirty-five hectares and surpassing even Karnak in its day. It was fronted by two colossal quartzite statues, each eighteen metres tall and weighing seven hundred and twenty tons, carved from single blocks quarried near modern Cairo and dragged six hundred and seventy-five kilometres overland to Thebes. These were the Colossi of Memnon, depicting the seated pharaoh with his hands on his knees, wearing the nemes headdress and flanked by smaller figures of his mother Mutemwiya and his wife Tiye. The temple itself was largely destroyed by earthquakes and Nile floods in antiquity, its stone quarried away by later builders, but the colossi remained. In 27 BCE an earthquake cracked the northern statue from the waist up, and thereafter it began to "sing" at dawn, a whistling or humming sound caused by the night dew evaporating in the morning heat. The Greeks, who identified the statues with Memnon, the Ethiopian hero of the Trojan War, believed the sound was the voice of the dead warrior calling to his mother Eos, the dawn. Roman emperors including Septimius Severus came to hear it, and one hundred and seven Greek and Latin inscriptions carved into the legs of the statues record the visits of ancient tourists who claimed to have heard the oracle speak. The singing stopped after Septimius Severus repaired the cracks in 199 CE, but the name Memnon endured.

The pharaoh's personal residence was the Malkata Palace, a sprawling complex south of Thebes that included audience halls, harem quarters, kitchens, and a vast artificial lake called the Birket Habu, excavated for the king's pleasure. He celebrated three Sed festivals, the jubilee rituals that renewed a pharaoh's divine authority, an extravagance that testified both to his long reign and to his determination to be recognised as a god on earth. Hundreds of statues survive from his reign, more than from any other pharaoh, depicting him in every material from granodiorite to glazed faience, wearing every crown from the double plumes of Amun to the blue war crown. He was the first pharaoh to be worshipped as a deity during his own lifetime, his cult statues receiving offerings in temples across the land.

Amenhotep III died in the thirty-eighth or thirty-ninth year of his reign, around 1350 BCE, and was buried in tomb KV22 in the Valley of the Kings. His mummy has been identified and now rests in the National Museum of Egyptian Civilisation. He was succeeded by his second son, Amenhotep IV, who within a few years would abandon the name of Amun, close the temples of the old gods, and declare that only the sun disk Aten was divine. The glittering world Amenhotep III had built would be dismantled by his own heir, yet the father's legacy proved stronger than the son's revolution. After Akhenaten's death, the old religion was restored, and Amenhotep III was remembered as the model of what a pharaoh should be: not a warrior but a builder, not a conqueror but a diplomat, a king so magnificent that the gods themselves had shaped him from clay.