Aortic stenosis is a common, potentially fatal condition that is set to become an increasing public health burden. Once symptoms develop, there is an inexorable deterioration with a poor prognosis. Despite this, there are no medical therapies capable of modifying disease progression, and the only available treatment is aortic valve replacement, to which not all patients are suited. Conventional teaching suggests that aortic stenosis is a degenerative condition whereby "wear and tear" leads to calcium deposition within the valve. Although mechanical stress and injury are important factors, it is becoming increasingly appreciated that aortic stenosis is instead governed by a highly complex, regulated pathological process with similarities to skeletal bone formation. This review discusses the pathophysiology of aortic stenosis with an emphasis on the emerging importance of calcification, how this can be visualized and monitored using noninvasive imaging, and how our improved knowledge may ultimately translate into novel disease-modifying treatments.