Leiden is a city in the province of South Holland, Netherlands that is an agglomeration of four suburbs. Located on the Oude Rijn delta, Leiden was formed on an artificial hill at the convergence of two rivers, the Old and New Rhine. A water town, or grachtenstad, Leiden was built on land reclaimed from bodies of water, so it has a non-uniform layout. Because the land was divided by the measure of bodies of water and joining of suburbs, the boundaries were fixed in relation to natural features and yield “organic” patterns and divisions. Specifically, the city is intersected by numerous small canals with tree-bordered quays. Like most water towns, the canal-streets were kept narrow and building blocks are long and narrow, surrounded by more canals around the area that limit expansion. Strategic fortifications for Leiden were thoughtfully planned around the city’s irregular streets, such as the circular tower castle de Burcht that was built on an earthen mound at the junction of the two rivers.