Construction of Nan Madol, a megalithic complex made from basalt lava logs in Pohnpei began as early as 1200 CE. Nan Madol is offshore of Temwen Island near Pohnpei, consists of a series of small artificial islands linked by a network of canals, and is often called the "Venice of the Pacific". It is located near the island of Pohnpei and was the ceremonial and political seat of the Saudeleur Dynasty that united Pohnpei's estimated 25,000 people until its centralized system collapsed amid the invasion of Isokelekel. Isokelekel and his descendants initially occupied the stone city, but later abandoned it.