Nice map Borry.
Yes, go back a page and there are a few links to the sand castle.
It's interesting that it's due south of Alexandria but it's also very close to the Tropic of Cancer.
22.51° north, 30.73° east compared with 23°26′N 25°0′E for the Tropic of Cancer. Although that Tropic does move as the Mexicans have noted on their road signs.
Carretera 83 (Vía Corta) Zaragoza-Victoria, km 27+800. Of all crossings of the Tropic of Cancer with Mexican federal highways, this is the only place where the latitude is marked with precision and where the annual drift between the years 2005 and 2010 can be appreciated.
More linear than circular. I wonder where it was when this stone circle was built?