A form of real estate investing was most likely practiced by ancient cave dwellers.

Anthropologists talk about something they call a “defensible property.” This is a dwelling that provides a measure of safety, comfort and security, and thus, had value. So-called cavemen almost certainly bargained with the forms of wealth they had at the time to secure a decent place to live.

Thousands of years later humankind had developed the city-state. A new study has shown that ancient Athens, Greece had developed a real estate investment industry. Recently discovered inscriptions from Olynthos in the Chalkidiki show that citizens of Athens were buying and selling homes or properties in ways that are similar to today.

Scholars say that by the Middle Ages in Europe, the development and marketing of real estate had become a popular method of generating income. It was the European brand of real estate business that eventually made its way to the New World. The real estate investment industry began to flourish soon after Europeans began colonizing the Americas.

What truly made real estate investment take off and evolve into the complex art  it is today is the American-style free-market capitalism being practiced in a society grounded by democratically elected governments.

A major fuel for the practice of real estate investment in the United States was a growing population that was spreading westward rapidly and gobbling up new land as they did so. Although settlers began claiming pieces of land to buy and sell, aboriginal tribes that predated the settlers considered land a shared resource, so this change was a massive shift from pre-colonial times.

As the 20th Century dawned, real estate investment was poised to reach new levels of complexity and wealth-generating potential. The tremendous economic prosperity of the 1920s generated a historic surge in real estate investment activity. This was stymied by the Great Depression, of course, which caused much of the real estate sector to crash.

However, the post-World War II period saw a resurgence of real estate investment that reached dizzying new heights. Nareit estimates that the U.S. real estate industry in the United States today is valued at $14 trillion to $17 trillion annually.