The Marchitecture is a cognitive architecture for autonomous development of representations. The goals of The Marchitecture are domain independence, operating in the absence of knowledge engineering, learning an ontology of parameterized relational concepts, and elegance of design. Representation change comes about through a pair of primary mechanisms, which we term "assimilation" and "accommodation". Accommodation is the formation of concepts, which builds an ontology, and assimilation amounts to explaining or recasting data in terms of the developed ontology. This model is inspired by Piaget's Constructivist theory of learning. The Marchitecture assumes an ample amount of raw data to develop its representations, and it is therefore appropriate for long lived agents.