Final answer:
The Basilica di Sant'Andrea by Leon Battista Alberti displays a strong appreciation for Roman imperial architecture through its use of Corinthian capitals, a grand central arch, and an imposing barrel vault.
Step-by-step explanation:
The building of Leon Battista Alberti that most clearly shows an appreciation of the spatial character of Roman imperial architecture is the Basilica di Sant'Andrea. This is evident from the combination of ancient Roman forms that Alberti incorporated into its design. The façade of the Basilica features four giant pilasters with Corinthian capitals supporting an entablature and pediment, reminiscent of ancient temples like the Pantheon. Additionally, the grand central arch of the façade, flanked by triumphal arch-like side doors, echoes the structure of monuments such as the Arch of Constantine. Sant'Andrea's interior also has an awe-inspiring barrel vault, the largest since antiquity, which undoubtedly creates a monumental spatial experience for the visitors, drawing connections to the grand interiors of Roman imperial buildings.