Masefau Defensive Fortifications - Credit: Wikimedia Commons
The Masefau Defensive Fortifications consist of a pair of concrete pillboxes on the shores of Masefau Bay on the island of Tutuila in the United States territory of American Samoa. These octagonal structures differ from others found in western Tutuila in that they have no separate interior space for the storage of ammunition. The structures were exposed by a typhoon in 2009. Read more on Wikipedia
Source: en.wikipedia.org