Final answer:
Roman architects utilized massive concrete construction to create innovative interior spaces in buildings like the Pantheon, employing techniques such as plasticity and poche.
Step-by-step explanation:
Roman architects of the imperial period took advantage of the possibilities of massive concrete construction to create new visual, compositional, and lighting effects in the building's interior. The Pantheon is a notable Roman building that showcases these techniques. One technique is plasticity, which refers to the malleability of concrete allowing architects to shape the interior space without being limited by structural supports. Another technique is poche, which refers to the spaces carved out of the wall's thickness to create alcoves and other design elements. These techniques can be seen in the Pantheon's coffered dome and oculus, which create a visually striking and well-lit interior space.