Between 1926 and 1928, the philosopher Ludwig Wittgenstein designed a house for his sister in Vienna (the Kundmanngasse). This book aims to clarify the relation between that house and Wittgenstein s early philosophy. The starting point of its main argument is a remark from Diktat für Schlick (c. 1932-33) in which Wittgenstein proposes an analogy between ornaments and nonsensical sentences. The attempt to extract from it an account of the relation between the Kundmanngasse and the Tractatus Logico-Philosophicus (1921) leads to the writings of Adolf Loos (whose influence Wittgenstein recognized). The discussion of Loos s writings suggests that the analogy should be understood, not as one between actual ornaments and nonsensical sentences, but as one between Loos s and Wittgenstein s uses of these notions. So understood, it favors the (so-called) resolute reading of the Tractatus and reveals that both Wittgenstein s use of nonsense and Loos s use of ornaments are means to the end of promoting self understanding. The book concludes that both the Kundmanngasse and the Tractatus are results of Wittgenstein s efforts at this kind of self understanding. These can be construed as ways of acknowledging our humanity, which in turn can be seen as a unifying element of Wittgenstein s philosophy.