Engineering

Riddle solved: Why was Roman concrete so durable?

The ancient Romans were masters of engineering, constructing vast networks of roads, aqueducts, ports, and massive buildings, whose remains have survived for two millennia. Many of these structures were built with concrete: ...

Business

Uber investment deepens ties with scooter startup Lime

Uber is leading a $170 million investment in scooter- and bike-sharing startup Lime, in a move that deepens the ties between the two "sharing economy" platforms, the companies said Thursday.