Five interferometer mirrors and two benches are suspended to superattenuators in the central building.
The superattenuators are a complex mechanical system used to isolate the mirrors and benches from the seismic noise. Moreover, they are enclosed in vacuum in order to isolate them from acoustic noise. Five superattenuators are visible in this picture, four with the vacuum enclosure closed ("towers") and the new one added for Advanced Virgo being mounted.
Credits: Cyril Frésillon/Virgo/Photothèque CNRS