The Romans were masters of engineering, constructing vast networks of roads, aqueducts, ports, and massive buildings, whose remains have survived for two . Many of these structures were built with concrete: Rome's famed Pantheon, which has the world's unreinforced concrete dome and was dedicated in A.D. 128, is still intact, and some ancient Roman still deliver water to Rome today. Meanwhile, many modern concrete structures have crumbled after a few decades. Researchers have spent decades trying to figure out the secret of this ultradurable ancient construction material, particularly in structures that endured especially harsh conditions, such as docks, sewers, and seawalls, or those constructed in seismically active .
(Excerpt from 'Riddle solved: Why was Roman concrete so durable?’, news.mit.edu, 2023)