Imhotep, King Djoser's architect, constructed the first pyramid around 2780 BCE by stacking six mastabas, each smaller than the one below, to create a pyramid that rose in steps. This Step Pyramid is located at Sakkara, close to Memphis, on the western bank of the Nile River.

The oldest and largest of these pyramids was built for the pharaoh Khufu, who ruled Egypt during the 26th century BCE. The pyramid, known as the Great Pyramid of Giza, is located on the outskirts of Cairo and is one of the most recognizable and iconic structures from ancient Egypt.

The Great Pyramid is thought to have been built over a 20-year period during Khufu's reign. It was constructed using around 2.3 million limestone blocks and stands 147 meters (481 feet) tall.

The pyramid was originally covered in white limestone, which would have made it glitter in the sun, but most of the limestone has since been removed and used to build other structures.

The ancient Egyptians built a total of around 138 pyramids, most of which were built during the Old and Middle Kingdom periods (26th to 16th century BCE). The Great Pyramid of Giza is the largest and most well-known of these pyramids, but there are many other significant pyramids in Egypt, such as the Pyramid of Khafre and the Pyramid of Menkaure, which are also located at Giza, and the Red Pyramid and Bent Pyramid at Dahshur.

Characteristics of the pyramids

One of the most remarkable characteristics of the Egyptian pyramids is their precision and accuracy in construction. The pyramid was built with a very high level of accuracy, with the four sides aligning almost perfectly to the four cardinal points of the compass, and the corners aligning to within only a few seconds of arc.

The pyramid also contains several sophisticated architectural features, such as the Grand Gallery, the Queen's Chamber, and the King's Chamber, which was used for various religious and administrative purposes. The King's Chamber, located at the heart of the pyramid, contains a large granite sarcophagus that was intended to hold the pharaoh's mummy.

Another interesting feature of the pyramid is the network of corridors and shafts inside the pyramid which served as pathways for the pharaoh's soul to reach the afterlife, and also as a way for the pyramid to be ventilated.

The construction of the pyramids was a massive undertaking that required a huge workforce and a lot of resources. It is estimated that around 100,000 people were employed in the construction of the Great Pyramid of Giza, which took around 20 years to complete. The construction of the pyramid required the quarrying, transportation, and placement of around 2.3 million limestone blocks, each weighing an average of 2.5 to 15 tons.

To move and place these massive stones, the ancient Egyptians likely used a combination of ramps and levers. Some evidence suggests that ramps were built to pull the large stones up, while levers and pulleys may have been used to lift the stones into place. The pyramid's inner corridors and chambers were then cut into the limestone blocks using copper saws and chisels.

It's worth noting that the pyramid was not just a tomb, but a complex of structures, including a temple and a causeway, that served both religious and administrative purposes.

In any case, the Egyptian pyramids are not just a monumental achievement in ancient engineering, but also a testament to the ingenuity, organization, and skill of the ancient Egyptians. They also had a profound influence on the architecture and engineering of later cultures.

It is not clear who exactly built the pyramids, how did the ancient Egyptians manage to move those massive stones, and how they were able to get it such a precise shape. But it is believed that they built ramps to pull the large stones up and used a variety of techniques to shape and place the stones. It was also a big collective work, with a big workforce, and also a monumental achievement in ancient engineering.