The idea for Foundations came from my experience in the museum field, where I spent 15 seasons as a historical Interpreter in 18th and 19th century sites through New York and New England. I used many of these technologies routinely, and realized they were still useful, and could be built much faster and cheaper than many modern technologies to answer the same problems. Further, when I was young, I read the works of Issac Asimov, specifically his Foundations trilogy, wherein there is a group of scientists, engineers and technicians who preserve the technology of the intergalactic empire as it declines and collapses, shortening the predicted dark age by from 30,000 years to less than 10,000. The same Idea, applied to ancient technologies, carefully selected, could have a similar effect.
As you may be aware, there are several elements to Historic Technologies which make them very well suited to solving modern problems or inefficiencies, namely their Simplicity, Efficiency, Variety and Expediency. Historic technologies are for the most part very simple, which allowed a mechanic to design, build, and maintain them with a minimal amount of work. Further, this simplicity of parts and structures ensures reliability by allowing the least number of chances for something to break. Interlocking systems frequently fed off each other, using a waste product to feed another process.
The variety of historic technologies also allows one to address most any practical problem imaginable. These technologies were designed to aid in producing everything necessary to live comfortably, from food to clothes and consumer goods to tools. These designs need not be engineered from the ground up, or from an ephemeral idea, as they exist in both documentary and working variations, which provide detailed plans and instructions for their construction and employment.