We use (some say waste) a lot of land for the burial of our dead. This pyramid, proposed for London in the 19th century by Thomas Willson, would be one answer. It never caught on, and I think the reason is that, while we can forget the existence of cemeteries when we’re not visiting them, this massive structure would always be visible on the city skyline.
Click the image for more information. Hat tip We Waste Time.