What is a "Yōhaijo"?
Worshipping gods or Buddha those are in a faraway place is called "Yōhai ("遥拝")", and a "Yōhaijo ("遥拝所")" is a place to yōhai. Typically, the name of a yōhaijo refers to it's object of worship, like "〇〇-yōhaijo".
A yōhaijo is built to worship a god that is enshrined at a difficult place to visit, such as on a mountain or an island, or to worship another shrine that is located far away. Like a haiden, that is a place to worship the god of the honden not enshrining a god in it's self, a yōhaijo is not a place where a god would be enshrined.
Most yōhaijo are built in the precincts of a shrine, but some yōhaijo have it's own precinct outside a shrine. Yōhaijos are built in various styles, most are just stone monuments, some are built as a building. Most yōhaijo just face the direction of the object of faith, but some are built where the object is visible.