Roman engineering is often celebrated for its monuments — aqueducts, roads, amphitheaters — but the technical knowledge that produced these monuments was largely empirical, without the mathematical mechanics that would have allowed Romans to explain why their structures worked.

The arch and the vault are the defining structural forms of Roman architecture. The semicircular arch distributes load around its curve into the supports, allowing stone and brick structures of spans that would be impossible with simple lintel construction. Roman engineers understood this through practice and observation rather than structural theory; Vitruvius' De Architectura, the only surviving architectural treatise from antiquity, is primarily practical guidance rather than engineering science.

The development of Roman concrete (opus caementicium) was the key innovation that enabled Roman monumental construction. The discovery that volcanic ash (pozzolana) mixed with lime and water produces a hydraulic concrete that sets underwater and gains strength over time gave Roman builders a material that was cheaper, more flexible, and structurally different from stone. The Pantheon's unreinforced concrete dome — still the world's largest after 1,900 years — was made possible by the use of progressively lighter aggregate toward the crown.

Roman roads used a layered construction system — excavated bed, drainage layer, rubble and mortar base, finished surface — that produced roads durable enough to remain in use for centuries. The straightness of Roman roads is sometimes overstated (they curved around major obstacles), but their directness compared to pre-Roman trackways reflects genuine surveying skill using the groma and the chorobates.