Mine was [The Ancient Engineers, by L. Sprague de Camp](https://www.goodreads.com/book/show/1120788.The_Ancient_Engineers). Though he's primarily known as a sci-fi writer, the author did this as a well referenced, fact based history of ancient technologies and engineering. It delivers a great perspective of how knowledgeable and advanced ancient people actually were. Basically how they were just like us in an earlier time, and how one simple invention or discovery was used as a stepping stone onward and upward to the advancement of civilization as a we know it today. It's a great easy read and an eye opener when it comes to advancements in technology in general. How even something as simple as the innovation of adding a stirrup on a saddle can lead to great improvements in human history.