Heavy tank
The Char 2C was one of the largest tanks ever produced. At the start of World War II, France and the Soviet Union were the only countries to have inventories of heavy tanks, such as the Char B1, T-35, and KV-1. The Matilda II was designed under the British infantry tank concept which is similar to the heavy tank having thick armor and weighing more than their other tanks. It’s usually separate because they have less firepower with their cruiser tanks (comparable to mediums) at the time having the same main armament but more machine guns. Later war examples were the German Tiger I and II, as well as the Soviet IS series. Note that "heavy" versus "medium" is more a question of tactical roles than weight; the Panther, for example, was a "medium" tank that outweighed most Allied "heavy" tanks.
Cisterns of Tawila
The Cisterns of Tawila, or the Tawila Tanks, are the best-known historic site in Aden, Yemen. The site consists of a series of tanks of varying shape and capacity. They are connected to one another and located in Wadi Tawila to the southwest of Aden’s oldest district, Crater. Originally there were about 53 tanks, but only 13 remain following a succession of renovations, including those done by the British in the 19th century. The existing tanks have a combined capacity of about nineteen million gallons. The tanks were designed to collect and store the rain that flows down from the Shamsan massif through Wadi Tawila, and to protect the city from periodic flooding. The largest of the tanks are the Coghlan Tank at the center of the main site and the large, circular Playfair Tank, located at the lowest point, outside the main site.