In the past three decades, cosmic microwave background (CMB) has provided a wealth of information on the origin and the history of the universe. From motivating the theory of the Big Bang, to providing tests for the standard model of cosmology; from measuring the Hubble constant, to constraining the mass of the neutrino; from testing the matter composition of the universe, to shedding light on the cluster evolution, CMB has truly become one of the most critical subjects of modern cosmology. However, to fully realize its potential and to achieve a level of accuracy that none has achieved before, large observatories equipped with ten times the detectors as the current generation experiments are needed. Such is the time that Simons Observatory (SO) collaboration came together, and proposed a Large Aperture Telescope (LAT) and an array of Small Aperture Telescopes (SATs) that met such criteria. Built upon the expertise from the current generation ground-based telescopes such as the Atacama Cosmology Telescope (ACT) and the South Pole Telescope (SPT), SO will initially deploy a total of 60,000 detectors, split about evenly between the LAT and SATs, with the potential to double the detector count in the LAT. Naturally, it is no easy undertaking to build a receiver capable of such feat for the LAT. In this thesis, I will recount the science cases put forth by SO, and walk through our journey in the designing, making, and testing of the Large Aperture Telescope Receiver (LATR).