Care-a-Lot Castle is one of the few constants across the Care Bear story; it is one of the places where important meetings are held and other events in Care-a-Lot.
As Care-a-Lot Castle is often only seen in the background of the shows, there has been a lot of room for changes to the design. At one point, the whole castle was made of clouds with a large heart shaped door; later it was a solid building with a pink drawbridge and rainbow coloured spires, which was very similar to the greeting card and comic book design.
Throughout the Care Bear story, Care-a-Lot castle has become less and less important to the plot. When the Care Bears were greeting card characters, almost all of the large promotional pieces were back dropped by Care-a-Lot castle.
In the first animated series by DiC, (Care Bears), the castle was prominent in the story line, while in the Nelvana series, (The Care Bears Family), more of the important meetings were held in the Hall of Hearts as Care-a-Lot castle is not shown in the series.
As of the newer shows, the castle has made no appearance except as a toy.
Care-a-Lot castle was sold as an add-on to the early bears in the 80's. It was a pigeon hole structure that the bears sat in, while the newer Care-a-Lot castle toy was sized to fit plastic figurines.