The Jiangmen Underground Neutrino Observatory (JUNO) is the state-of-the-art liquid-scintillator-based neutrino physics experiment under construction in South China. Thanks to the 20 ktons of ultra-pure liquid scintillator (LS), JUNO can perform innovative and groundbreaking measurements like determining neutrino mass ordering (NMO). The experiment is being constructed in a 650 m underground laboratory (1800 m.w.e.), about 52 km from the Taishan and Yangjiang nuclear power plants. The JUNO Central Detector (CD) will be equipped with 17,612 20-inch and 25,600 3-inch photomultiplier tubes (PMTs), respectively. JUNO CD energy resolution is expected to be better than 3% at 1 MeV and to have an absolute energy scale uncertainty better than 1% over the whole reactor antineutrino energy range. In addition, the JUNO experiment also has a satellite detector, the Taishan antineutrino observatory, to measure the reactor antineutrino energy spectrum with high precision. Beyond NMO, JUNO will measure the three neutrino oscillation parameters with a sub-percent precision. Moreover, the JUNO experiment is also expected to have important physics reach with solar neutrinos, supernova neutrinos, geoneutrinos, and atmospheric neutrinos, and searches for physics beyond the Standard Model such as nucleon decay. This paper will present the detector design and installation status of the different JUNO subsystems.