I was thinking about the Gelfand-Naimark theorem asserting the isometric * isomorphism between a commutative $C^*$-algebra (with unit) $\mathcal{A}$ and the $C^*$ -algebra of continuous complex-valued functions on its spectrum (via the Gelfand transform). Explicitly: let $spec(\mathcal A)$$\operatorname{spec}(\mathcal A)$ denote the spectrum of $A$ and $C(X)$ the algebra of complex continuous functions on $X$. Then spec and C define contravariant functors from commC* alg to CompHausTop, which (correct me if i'm wrong) establish an equivalence between the two categories. Gelfand-Naimark theorem has a non-commutative analogue, which is based on the so-called GNS construction and which shows that every non commutative $C^*$ -algebras has a faithful isometric * -representation on a Hilbert space $H$. In this case I can't see an analogue of the preceding equivalence of categories, which is equally meaningful. Does it exist?