There is, then, an overriding desire to respect these sites, rather than just breaking them open for anyone to gaze upon. And, also, because they are tombs, many of the chambers and rooms within them were sealed off when they were built & so it's not as though someone could just open a door into them, anyway.
You can visit the Red Pyramid every day from 08:00 a.m. to 04:00 p.m. in the winter, and from 08:00 a.m. to 05:00 p.m. during summertime.
