The Observatorio Astrofísico de Javalambre (OAJ) is an astronomical facility located at the Pico del Buitre of the Sierra de Javalambre, in Teruel, Spain, at 1957m over the sea level. It has been conceived and defined to carry out large sky astronomical surveys from the Northern hemisphere with wide field telescopes and panoramic instrumentation. The OAJ is fundamentally organized around two large field-of-view (FoV) telescopes with their corresponding panoramic instrumentation for direct imaging that allows to carry out world-leading photometric surveys with an ample spectrum of key astrophysical applications. In this sense, the OAJ has already started to provide relevant data to essentially all the main research domains in Astrophysics and Cosmology. The two telescopes at the OAJ are the Javalambre Survey Telescope (hereafter, JST/T250), a 2.55m telescope with a FoV of 3 deg diameter, and the Javalambre Auxiliary Survey Telescope (hereafter, JAST/T80), a 0.83m telescope with a FoV of 2 deg diameter. Both of them are equipped with panoramic instrumentation designed to maximize the focal plane coverage while maintaining the image quality, namely JPAS-Pathfinder (interim) and JPCam for JST/T250, and T80Cam for JAST/T80. In particular, JPCam, with more than 1.2 Gpixels in a mosaic of 14 large-format CCDs (9.2k x 9.2k each) is amongst the largest astronomical cameras in the world. The large Etendue of the JST/T250 and JAST/T80 telescopes, their panoramic instrumentation, and the more than 70 unique optical filters available at the cameras of the two main telescopes makes the OAJ an unprecedented astronomical facility at this moment. Given that the telescopes will be mostly dedicated to predefined long-term projects, they will be the most efficient instruments to perform large scale, multi-filter astronomical surveys in reasonably short periods of time. The OAJ includes the UPAD Data Center with capacity to provide raw, reduced and calibrated data on a quasi real time basis and to archive and allow external access to the whole scientific community.