In regards to the question, "Dykes" are constructions specifically found in Holland. Dykes, also known as dikes, are barriers constructed to prevent flooding by preventing the overflow of water from rivers, oceans, or lakes. Holland, which is also known as the Netherlands, is known for its extensive network of dykes due to its low-lying geography and proximity to water bodies. The construction of dykes in Holland has been an essential practice for centuries to protect its land from being submerged during high tides or storms. It is important to note that while other countries may also have similar flood prevention structures, Holland is particularly well-known for its expertise and extensive use of dykes.