The second generation of gravitational wave detectors represents the instrument that
finally observed Gravitational Waves (GWs). This milestone was achieved thanks to the
development of continuous technological solutions adopted to suppress all possible
sources of noise that limit the sensitivity of the instrument within the detection band
and mask the possibility of observing the weak GW signal that is of the order of
10^{-18}m/rtHz.  If the detection band of the advanced detectors (2nd generation
detectors) varies from 10 Hz to 10 kHz, the plan for third-generation GW antennas, such
as the Einstein Telescope (ET), aims to improve the current sensitivity by approx a
factor of 10 and at the same time, extend the observation in the low-frequency region up
to about 2-3 Hz where the improvement required with respect to the present experimental
limits is more than 5 orders of magnitude higher. In this talk, I will give a short
overview of Advanced Virgo (AdV) and ET status and what we can learn from Virgo for the
development of the Einstein Telescope (ET).