I don't think I've ever seen a Portal Tomb. I do know that staying on site doesn't add to clarity. That comes from learning abstract facts and then applying them to a site, or event. I do know that when you find stuff that people will appear out of the woodwork to proclaim you as deluded, mistaken, or worse. I also know that an old gadgee found some very interesting things looking at the shadows cast by Cumbrian circles around the calendar days. Shadows are so ephemeral and not 'scientific'. I also know that stone structures can appear to be unstable for years and then topple or fall, seemingly at random, when there's a deluge or a fast thaw (a stonemason has his ears wide open for the the scrapy rumble that presages collapse and gets out of the way fast). You don't mess with gravity! But where are the measurements of the squircle? I know of an animal called the squirrcodile - found in the Ohio wetlands - quite a shy creature, scampers amongst trees, but with a prehensile tail and a double row of razor-sharp incisors.