Short answers, pulled from the story.
Eleven aqueducts brought a thousand cubic metres (260,000 US gallons) of water into Rome each day. Most of this water served public uses such as baths and sewers rather than private homes. Per capita water usage in ancient Rome matched that of modern cities like New York.
Trajan's Bridge over the lower Danube, constructed by Apollodorus of Damascus, was the longest Roman bridge ever built. It remained the longest bridge in the world in both overall and span length for over a millennium after its construction.
The Pons Aemilius, built in 142 BC, is the oldest Roman stone bridge in Rome. It was later renamed Ponte Rotto, meaning broken bridge.
High-quality Roman roads were built in five layers. From bottom to top these were the pavimentum (one inch of mortar), the statumen (one foot of stones bound in cement or clay), the rudens (ten inches of rammed concrete), the nucleus (twelve to eighteen inches of rolled concrete layers), and a final surface of silex or lava polygonal slabs.
Barbegal, located in southern France near Arles, was a Roman mill complex comprising sixteen overshot water wheels arranged in two parallel lines down a hillside, all fed by a single aqueduct. The site's capacity has been estimated at 4.5 tons of flour per day, sufficient to supply bread for approximately 12,500 people in the town of Arelate.
Roman miners used hydraulic mining methods including hushing, where a wave of water was suddenly released from tanks to strip topsoil and expose gold-bearing bedrock, and fire-setting, where rock faces were heated to crack them. At Dolaucothi in west Wales, at least five aqueducts were cut from adjacent rivers to supply the gold-mining operations. Las Medulas in north-west Spain was one of the largest alluvial gold-mining sites, developed on a very large scale in the early part of the 1st century AD.