The Very Large Telescope array (VLT) is the flagship facility for European ground-based astronomy at the beginning of the third Millennium.  

• It is the world’s most advanced optical instrument, consisting of four Unit Telescopes with main mirrors of 8.2m diameter and four movable 1.8m diameter Auxiliary Telescopes.  

• The telescopes can work together, to form a giant ‘interferometer’, the ESO Very Large Telescope Interferometer, allowing astronomers to see details up to 25 times finer than with the individual telescopes. The large telescopes are named Antu, Kueyen, Melipal and Yepun. 

Source: NASA