Added in the Rise and Fall expansion pack.
The Plantation is a great improvement, because it not only gives you access to the great majority of luxury resources, but also increases (or provides) their Gold output. It also increases housing by +0.5, as like farms, they provide living quarters. What's more, it doesn't destroy terrain features like Forests and Jungles anymore, allowing them to continue conveying bonus yields to the tile!
Of course, Plantations may only be built on certain resources, not wherever you please.
Not just a fancy sort of farm (although some of them have really nice houses), a plantation is a large agrarian enterprise generally devoted to a single valuable "cash" crop – cotton, tobacco, tea, sugar cane, rubber, coffee and such – tended by resident laborers. The crops are usually, but not always, indigenous to the region, and most of the plantations in history were in tropical or semi-tropical climes. The crops did well with all the rain and heat, and it meant the plantation owner didn't have to waste money keeping the workers warm. As Europeans spread their empires around the globe, they took the plantation formula with them to the Americas, India and Africa. The produce was not meant for local consumption, but was shipped out to the markets of Europe where the civilized folk could appreciate this rich bounty.