The ir. D.F. Woudagemaal is the largest still operational steam-powered pumping station in the world. On October 7, 1920 Queen Wilhelmina opened the pumping station. It was built to pump excess water out of Friesland, a province in the north of the Netherlands.
In 1967, after running on coal for 47 years, the boilers were converted to run on heavy fuel oil. It has a pumping capacity of 4,000 m³ per minute. The pumping station is currently used to supplement the existing pumping capacity of the J.L. Hooglandgemaal in case of exceptionally high water levels in Friesland; this usually happens a few days per year.
Since 1998 the ir. D.F. Woudagemaal has been listed on the UNESCO World Heritage Site list. The station is open for visitors and tours are given regularly.
References:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.