Our knowledge of ancient artillery derives primarily from several ancient technical texts. The most important among them are the works of Philon, Heron and Vitruvius. Taken in combination, these texts are sufficiently detailed to allow reconstruction of functioning artillerypieces, and the first reconstructions of catapults were made as early as the middle of the nineteenth century, long before any actual find was known. The second source for our knowledge of ancient artillery consists of representations of catapults found on Greek and Roman reliefs. In spite of their small number these reliefs are a significant complement to the written texts, not only because they show technical detail which might otherwise be controversial, but also because most of them can be dated within narrow bounds and in this way give some hints at the direction of development of ancient artillery. But the chances of finding new texts or new reliefs are very small. So actual finds of ancient catapults in archaeological excavations constitute a third source, which will gain increasing importance, because there are fair chances of finding remains of catapults at a number of sites.