ETpathfinder involves the construction of a state-of-the-art R&D facility for interferometry with flexible high-tech laser setups. With this, extensive research can be done into gravitational waves. To be able to carry out this research, new technologies are needed, such as the use of highly cooled silicon mirrors with new coatings, to replace the usual quartz glass. The vacuum requirements of the system in which laser light propagates and the suppression of vibrations explore the limits of what is currently technologically feasible. Moreover, everything must be accommodated in an extremely dust-free environment or 'clean room'. The universities of Maastricht, Eindhoven, Ghent, Leuven, Hasselt and Antwerp will collaborate with companies on this technological innovation. German universities are also involved in the research. Because of its unique character, ETpathfinder will also become an attraction for international research on high-precision measurement techniques, seismic insulation, measurement and control software, cryogenic technology and (quantum) optics. With ETpathfinder, necessary tests can be done which can then be carried out on a large scale in the ultimately planned European Einstein telescope. This telescope is expected to be built in the coming decade. Geologically speaking and due to the presence of a number of top research institutes and high-tech industries, the Netherlands-Flanders region is a promising location for the telescope.