Von Staudt was the most original and profound pure geometer of the German School. He realized that there were two critical issues in synthetic projective geometry as developed by Steiner and Chasles. The first was the definition of cross-ratio, which, although a projective invariant, was defined by them in terms of lengths and angles, which are not. The second was the vague definition of imaginary points and in general their unsatisfactory treatment of imaginary objects. In this chapter it is described in detail how in his Geometrie der Lage, published in 1847, von Staudt succeeded in making the principles and methods of the nascent projective geometry independent of metrical considerations. In particular, it is discussed here his notion and classification of fundamental forms; their projective transformations; and his theory of curves of degree two, that are viewed as fundamental curves via a particular type of projective correspondence (polarity or polar system). With the supplements that followed this work, the Beiträge zur Geometrie der Lage which appeared between 1856 and 1860, von Staudt succeeded, by using the notions of involution and the original one of “throw”, in giving a rigorous purely geometric definition of imaginary points, lines, planes and other figures, and extending to this objects the incidence laws which govern the real ones. All this is discussed here in detail. Then, it is commented upon the reception of von Staudt’s work, especially by Cremona, and its popularization through Reye’s Der Geometrie der Lage, which appeared in 1866. Finally, it is remarked that von Staudt’s work gave origin to the important debate on the proof of its fundamental theorem and the foundations of projective geometry, a debate that later exited in the process of its axiomatization.