This is where Divination classes are taught at Hogwarts. It is located in the North Tower. It is accessible through a circular trapdoor and is described as looking like a cross between somebody's attic and an old-fashioned teashop.
During the winter months, the tower is very cold, to the point that one has to be careful with ice on the higher landings. A tightly spiralling staircase leads from the bottom of the tower on the seventh floor up to a door leading out onto the battlements.
The Room of Requirement is a secret room within Hogwarts that only appears when a person is in great need of it. The room then transforms itself into whatever the witch or wizard needs it to be at that moment in time.