This chapter offers a general overview of the lime industry in relation to the built environment. The vital role of lime in cement making is also discussed. The production of lime from limestone calcination is carbon and energy-intensive requiring more than 3000 kJ per kg of lime and with processing temperatures around 1000 °C. In cement making, even higher temperatures (1600 °C) are required for the formation of the targeted calcium-rich clinker phases. More than half of the carbon emissions from lime making arise due to the process chemistry where calcium carbonate is thermally decomposed into calcium oxide and carbon dioxide gas. The use of lime in construction dates back thousands of years; since then, the fundamental principles of lime production, based on thermal calcination, has not changed. This is mainly because, until recent breakthroughs, society believed this to be the only way. Although the calcination process is industrially robust and its efficiency has been improving over the years, process improvements alone are not sufficient to achieve Net Zero and our climate goals. A description of novel approaches that avoid thermal calcination, and which have the potential of abating the carbon emissions from lime and cement manufacturing, are highlighted as they represent genuine solutions for the complete decarbonization of these industries that are crucial to our built environment.