In 1842, Lepsius was commissioned (at the recommendation of the minister of instruction, Johann Eichhorn, and the scientists Alexander von Humboldt and Christian Charles Josias Bunsen) by King Frederich Wilhelm IV of Prussia to lead an expedition to Egypt and the Sudan to explore and record the remains of the ancient Egyptian civilization. The Prussian expedition was modelled after the earlier Napoleonic mission, with surveyors, draftsmen, and other specialists.[4] The mission reached Giza in November 1842 and spent six months making some of the first scientific studies of the pyramids of Giza, Abusir, Saqqara, and Dahshur. They discovered 67 pyramids recorded in the pioneering Lepsius list of pyramids and more than 130 tombs of noblemen in the area.[4] While at the Great Pyramid of Giza, Lepsius inscribed a graffito written in Egyptian hieroglyphs that honours Friedrich Wilhelm IV above the pyramid's original entrance; it is still visible.[5] (photos and translation) In 1843 he visited Naqa and copied some of the inscriptions and representations of the temple standing there.[6]