Open-pit mining has been practiced since ancient times, with evidence of open-pit mines dating back to the Neolithic period. The earliest known open-pit mine is the Megalithic Temples of Malta, which were constructed around 3600-3200 BC. However, the modern concept of open-pit mining was developed during the 19th century in the United States. In the early 1800s, coal was being mined from open pits in Pennsylvania, and by the mid-1800s, open-pit mining was being used to extract copper and iron ore in Michigan and Minnesota. The first large-scale open-pit mine in the world was the Bingham Canyon Mine in Utah, which was opened in 1863 and is still in operation today.