Why are pyramids considered an important architectural achievement for the ancient Egyptians

The pyramids were great monuments and tombs for the kings. The Egyptians believed that a king's soul continued to guide affairs of the kingdom even after his death. To ensure that they would continue to enjoy the blessings of the gods, they preserved the pharaoh's body through the mummification process. They built the pyramids to protect the pharaoh's body, the pyramid was a symbol of hope because it would ensure the pharaoh's union with the gods. : D