Aberdeen is a city in northeast Scotland. It is Scotland's third most populous city, one of Scotland's 32 local government council areas and the United Kingdom's 39th most populous built-up area, with an official population estimate of 196,670 for the city of Aberdeen and 227,560 for the local council area. During the mid-18th to mid-20th centuries, Aberdeen's buildings incorporated locally quarried grey granite, which can sparkle like silver because of its high mica content. Since the discovery of North Sea oil in the 1970s, Aberdeen has been known as the off-shore oil capital of Europe. The area around Aberdeen has been settled for at least 8,000 years, when prehistoric villages lay around the mouths of the rivers Dee and Don. The city has a long, sandy coastline and a marine climate, the latter resulting in chilly summers and mild winters.