A full understanding of galaxy evolution requires a complete description of the role of cold gas as the primary fuel for star formation. The amount of cold gas in galaxies and the efficiency of gas conversion into stars determine many galaxy properties. Molecular gas observations, particularly through CO emission, are directly linked to star formation over cosmic time. While ALMA has made significant progress in this field, the limited scales of previous surveys and the potential effects of cosmic variance have limited the accuracy of cosmic gas mass density measurements. Here, I present the ALMA Calibrator Dataset (ALMACAL), a large untargeted survey of 1064 calibrator fields across the southern sky. Covering over 1000 square arcminutes and accumulating over 2000 hours of integration time, ALMACAL surpasses previous surveys in volume by at least ten times. I will present the methods for processing and imaging a subset of the highest-quality data. Initial findings will include the CO luminosity function based on detections found from ALMA Band 3 to 9 and the cosmic evolution of molecular gas up to redshift z~3. I will discuss the significance of these results in revealing the critical role of cold gas in the baryon cycle of galaxies.