The geophysics observatory at Neumayer Station II (NM-II), the successor base of the former Georg von Neumayer Station (GvN), has now been almost continuously in operation for nearly 25 years. The observatory programme with its main topics has been continued almost unchanged since its very beginning until a few years ago. The main subjects of the observatory work are currently the continuous recording of the Earth's magnetic field and the regional and global earthquake activities. For monitoring the regional seismicity a local seismographic network is operated with currently two remote stations on the ice rises Halvfar Ryggen and Søråsen. On Halfvar Ryggen a short period detection array was deployed in 1997, which has been the first one of this type in Antarctica. The geophysics observatory at NM-II Station closes a large gap in the worldwide network of geophysical monitoring stations which is rather wide-meshed in Antarctica. Data obtained are disseminated on a regular schedule to international data centres. In 2003 the infrasound station 127DE has been installed, which belongs to the International Monitoring System (IMS), which controls the compliance with the Comprehensive Nuclear-Test-Ban Treaty. This article will present the observatory in its entirety, especially the development from the first beginning with its problems to one of the most modern observatories in Antarctica at present. Also presented are some selected results from scientific work with observatory data with an emphasis on seismological research.