The Wall in Bahamas.

One researched record in Nassau in the Bahamas: one in private or limited access.

Map positions are missing for one of them: either no source supplied one, or the one supplied could not be right.

A further listing for the Bahamas is held in the catalogue as a draft, out of the map and the indexes until it has been researched.

Every record is labelled Reported: a credible source says the object is there, not that anyone has confirmed it in person. How claims are weighed is set out in the research methodology, and the reading room explains how the Wall came to be spread across places at all.