The Galactic Nucleus, at a distance of about 8 kpc and hidden behind
about 30 magnitudes of visual extinction by cool interstellar dust
along the line of sight, cannot be studied at visible, ultraviolet or
soft X-ray wavelengths. The available information about this nearest
centre of a galaxy comes from measurements at 
-ray, hard
X-ray, infrared, (sub)millimetre and radio wavelenghts. A remarkable
variety of structures on scales ranging from kiloparsecs down to the
subparsec level has been observed, among them some of the most
mysterious and bizarre astronomical structures known. There is very strong evidence for the existence of a massive black hole
(several million solar masses) at the very core of our Galaxy.
The research at Stockholm Observatory concentrates on the distribution and kinematics of molecular cloud structures and their physical and chemical properties, as well as their interactions with the radio continuum components, from the inner parsec out to about a hundred parsecs from the Galactic Centre.