Its said scientists in Alexandria developed a working steam engine.

The Aqueduct for sure.

Roman Roads outclassed all other transit infrastructure.

Used currency as a means of spreading propaganda, so I guess a prototype printing press.

Modern day Calendars are based off of the Julian Calendar created during Julius Ceasars Dictatorship.

They established a standing army effectively, and provided medals and awards to its legions as a reward.

Roman Baths.

I believe they invented Cement as well. No source though.

Thats enough for now