Namibia, on Africa’s southwest coast, is a large country with a harsh landscape. The towering and constantly shifting dunes of the Namib Desert, shown here in this aerial photo by Julian Walter, run right to the Atlantic Ocean and can reach up to a thousand feet high. [2048 x 1536]

Namibia, on Africa’s southwest coast, is a large country with a harsh landscape. The towering and constantly shifting dunes of the Namib Desert, shown here in this aerial photo by Julian Walter, run right to the Atlantic Ocean and can reach up to a thousand feet high. [2048 x 1536]

After a long trek we finally reached Gergeti Trinity Church placed 2170 meters (7120 feet) high in the majestic Caucasus Mountains! Once we got up to the top we were greeted by a friendly dog who lives up there!

After a long trek we finally reached Gergeti Trinity Church placed 2170 meters (7120 feet) high in the majestic Caucasus Mountains! Once we got up to the top we were greeted by a friendly dog who lives up there!

One of the oldest mosques in Iran is the Jameh Mosque of Isfahan. It is almost 1,250 years old and at 20,000 square feet it is the result of continuous construction, reconstruction, additions and renovations. (Link to more photos in comments.) Photo by Kuang Long Zhang. [962×1299]

One of the oldest mosques in Iran is the Jameh Mosque of Isfahan. It is almost 1,250 years old and at 20,000 square feet it is the result of continuous construction, reconstruction, additions and renovations. (Link to more photos in comments.) Photo by Kuang Long Zhang. [962×1299]

USS V-4 (Argonaut) and the diminutive USS O-2 in dry dock together. V-4 at the time was the largest submarine in the world at 381 feet long and the O-2 had a length of 172 feet. The dock is being flooded through ports in the dry dock gates at the rear of the image. PNS, 1928. [1200 x 800]

USS V-4 (Argonaut) and the diminutive USS O-2 in dry dock together. V-4 at the time was the largest submarine in the world at 381 feet long and the O-2 had a length of 172 feet. The dock is being flooded through ports in the dry dock gates at the rear of the image. PNS, 1928. [1200 x 800]