In the Prades Mountains (Tarragona) you can stargaze under the guidance of experienced guides with telescopes. It is a perfect place for stargazing because it is very dark (for those in the know: the brightness is about 21.4 mag/arcsec2). There is also a visitor center and planetarium. See https://www.parcastronomicprades.cat/ It’s really nice to spend the night in one of the spherical chalets, where the top is made of glass. Stargazing all night from your bed!
See https://www.xaletdeprades.com/