The paper presents a new composite CO survey of the Milky Way, combining 488,000 spectra obtained over two decades with the CfA 1.2 m telescope. This survey covers the entire Galactic plane and large local clouds at higher latitudes, offering 16 times more spectra, up to 3.4 times higher angular resolution, and up to 10 times higher sensitivity per unit solid angle compared to previous surveys. The composite maps provide detailed information on individual molecular clouds, suggest relationships between clouds and regions, and display the main structural features of the molecular Galaxy. The survey also includes a map of molecular column density predicted from far-infrared and 21 cm surveys, which agrees well with the observed CO map, indicating that only about 2% of the total CO emission at |b| < 32° lies outside the current sampling. The CO-to-H2 mass conversion factor X is calibrated using the predicted and observed CO intensity maps, showing a mean value of 1.8 ± 0.3 x 10^20 cm^-2 K^-1 km^-1 s^-1. The survey covers 45% of the sky within 30° of the Galactic equator and is likely nearly complete for clouds larger than a few degrees on the sky. The composite maps reveal the large-scale distribution and kinematics of molecular clouds, including the Taurus dark clouds, the second quadrant, the Cepheus and Polaris Flares, the first quadrant, the Ophiuchus, Lupus, and R CrA clouds, the Galactic center, the Chamaeleon and Carina regions, and the third quadrant. The survey highlights the thin, intense ridge of emission extending around the Galactic center and the well-defined lane of low-velocity clouds within 1 kpc of the Sun. The spatial distribution of low-velocity CO emission is compared to an optical panorama of the inner Galaxy, showing a tight correlation between CO emission and optical obscuration.The paper presents a new composite CO survey of the Milky Way, combining 488,000 spectra obtained over two decades with the CfA 1.2 m telescope. This survey covers the entire Galactic plane and large local clouds at higher latitudes, offering 16 times more spectra, up to 3.4 times higher angular resolution, and up to 10 times higher sensitivity per unit solid angle compared to previous surveys. The composite maps provide detailed information on individual molecular clouds, suggest relationships between clouds and regions, and display the main structural features of the molecular Galaxy. The survey also includes a map of molecular column density predicted from far-infrared and 21 cm surveys, which agrees well with the observed CO map, indicating that only about 2% of the total CO emission at |b| < 32° lies outside the current sampling. The CO-to-H2 mass conversion factor X is calibrated using the predicted and observed CO intensity maps, showing a mean value of 1.8 ± 0.3 x 10^20 cm^-2 K^-1 km^-1 s^-1. The survey covers 45% of the sky within 30° of the Galactic equator and is likely nearly complete for clouds larger than a few degrees on the sky. The composite maps reveal the large-scale distribution and kinematics of molecular clouds, including the Taurus dark clouds, the second quadrant, the Cepheus and Polaris Flares, the first quadrant, the Ophiuchus, Lupus, and R CrA clouds, the Galactic center, the Chamaeleon and Carina regions, and the third quadrant. The survey highlights the thin, intense ridge of emission extending around the Galactic center and the well-defined lane of low-velocity clouds within 1 kpc of the Sun. The spatial distribution of low-velocity CO emission is compared to an optical panorama of the inner Galaxy, showing a tight correlation between CO emission and optical obscuration.