Casting – whether in bronze, plaster or concrete – involves an exchange between formwork and the cast material. In this temporal process, water, air, heat, pigment, chemicals seep from the mould to the material cast, affecting surface quality, curing process, material distribution and solidity. As a complex temporal site that involves moulding, pouring, setting, curing and aging processes, casting yields knowledge that can inform our practices as architects. It can help us approach architecture as an act of sculpting in time while also considering time’s power to sculpt architecture. Bringing up questions of presence and absence, fixed and fluid, index and icon, solid and void, copy and repetition, positive and negative, casting also calls forth notions of representation in more than one way. Studying the multifaceted dimensions of time’s architectural actions via casting, this chapter considers the excavation at Pompeii, works by Tarkovsky and Scarpa, copies of Michelangelo’s Tondo and the concrete used at Ontario’s Scarborough College to offer some insights into the epistemological and phenomenological dimensions of time as a productive site of architecture.