After the Treaty of Guadalupe Hidalgo, two binational boundary commissions surveyed, mapped, and marked the US-Mexico boundary with stone and cast-iron obelisk-shaped monuments. By 1896 there were 258 monuments, dotting the borderlands with a unified set of architectural forms and sovereign claims. In this paper I used the still-extant obelisks and photographic archive of their production to consider the monuments within a critical history of obelisk construction and the images within a regime of landscape imagery representing an American racial imperialism. I consider the obelisk form as it was used to mark the progress of civilizational narratives and the conquest of imperial states. I claim the monument-obelisks, together with their photographic archive, produces an architectural-media narrative of imperialism and domination over Mexico, Mexican citizens, Indigenous populations, and the landscape. I understand landscape as a social construction based on relations between subjects, both human and not. Or, as W.J.T. Mitchell writes, a “medium of exchange,” a “natural scene mediated by culture.” The figure of the landscape, as much of a construction as the monuments and photographs, relies on previously established systems of knowledge and political ideologies. For the survey teams, ideologies of imperial right and racial domination were foundational to framing, relating, surveying, constructing, and penetrating the landscape. In this paper, I show how early boundary monuments produced an image of imperialism and I analyze the relation between boundary monuments and their photographic representation, placing them within a long lineage of landscape imagery that “pictures the nation” through tropes of racial hierarchy and virginal emptiness.