Hierarchies Database for the research project “Hierarchies” (project of Leonie Bosveld-de Smet and Harm Brouwer). To get insight into data, people like to arrange data in an ordered way and give them structure. Moreover visualization of these structured data allow to get even more insight. A well-known way to organize data is the hierarchical one. Categories of data are interconnected in a hierarchical manner. A common way to visualize hierarchically ordered information is the tree diagram. Tree diagrams are used in syntactic theories, such as X-bar theory, to represent the constituent structure of a sentence. They are also used in discourse theories, such as Rhetorical Structure Theory, to represent the argumentational structure of a text. Not only tree diagrams represent hierarchies in a visual way, also dendrograms, cladograms, box diagrams, brackets, and pyramids are used for the representation of hierarchically ordered data in various application domains. From a diagrammatic research view, it is interesting to collect the various types of information that lend themselves to a hierarchical ordering, with their visualizations, in order to investigate correspondences and differences between all these hierarchies. For this purpose, the research project needs a database which stores pictures of hierarchical visualizations, with appropriate descriptions, and characteristics, such as for example their application domain, the objects or concepts visualized, and the relationships involved.