The Jiangmen Underground Neutrino Observatory (JUNO) is a state-of-the-art, Liquid Scintillator (LS) based, neutrino physics experiment located in South China. With 20 ktons of ultra-pure Liquid Scintillator (LS), JUNO aims to achieve groundbreaking measurements, including the determination of Neutrino Mass Ordering (NMO) and the precise measurement of three neutrino oscillation parameters with sub-percent precision. The JUNO detector consists of a Central Detector (CD), a water Cherenkov detector, and a top tracker detector. The CD is equipped with 17,612 20-inch PhotoMultiplier Tubes (PMTs) and 25,600 3-inch PMTs, aiming at an energy resolution better than 3\% at 1 MeV. Four independent calibration systems are employed to ensure an absolute energy scale uncertainty of less than 1\% across the reactor antineutrino energy range. Beyond reactor neutrinos, JUNO has a broad physics program, including studies of solar neutrinos, supernova neutrinos, geoneutrinos, atmospheric neutrinos, and searches for physics beyond the Standard Model, such as nucleon decay. The detector installation was completed in December 2024, and the LS filling and system commissioning are currently underway. In this talk, I will present the detector design, construction milestones, and the commissioning performance of JUNO's subsystems.