In the re-imagined series, Cylon Basestars (also referred to as "baseships" or "Cylon battlestars") are by far the most prominent example of Cylon presence in the known universe. They easily dwarf a colonial battlestar and appear to be technologically superior in every way, including being able to release wings of hundreds of Cylon Raiders at the same time (according to the number of launch "slots" on the Basestar, it can release 792 Raiders).
Beyond this, not much is known. Basestar operations would suggest that they have large crew complements, although there is ample evidence to suggest their operations are largely automated. Indeed, the large complement of raiders would suggest on-board manufacturing facilities (The BSG Bible).
Its weapons complement indicates missiles on a similar principle to the United States' VLS system, which is capable of launching coventional or nuclear missiles.