  On September 2015, a century after Einstein's predictions of their existence,
the first gravitational waves (GWs) direct detection was performed by LIGO. On
August 17, 2017, the two Advanced LIGO and the Advanced Virgo interferometers
detected a GW produced by two merging neutron stars. The subsequent
localization of the source in the sky, thanks to the presence of a third
detector, led to the detection of the electromagnetic counterpart and follow-up
of the event by roughly 70 electromagnetic and neutrino telescopes. After the
first two data taking runs (O1 and O2), the LIGO-Virgo network detected 11 GWs
from 10 binary black holes and one binary neutron star. On April 1, 2019,
Advanced Virgo and Advanced LIGO started their third observing period (O3).
After an introduction on GW detection, I will give an overview on the Advanced
Virgo detector design, with a description of the technical choices made before
O3 and their consequences on the detector sensitivity. Finally, I will describe
the planned upgrades for the Advanced Virgo+ project.

Instrumentation and Methods for Astrophysics