Author Alan F. Alford interprets the entire Great Pyramid in the context of ancient Egyptian religion. Alford takes as his starting point the golden rule that the pharaoh had to be buried in the earth, i.e. at ground level or below, and this leads him to conclude that Khufu was interred in an ingeniously concealed cave whose entrance is today sealed up in the so-called Well Shaft adjacent to a known cave called the Grotto.[23] He has lobbied the Egyptian authorities to explore this area of the pyramid with ground penetrating radar.[24]