  We develop exceptional field theory for E$_{8(8)}$, defined on a
(3+248)-dimensional generalized spacetime with extended coordinates in the
adjoint representation of E$_{8(8)}$. The fields transform under E$_{8(8)}$
generalized diffeomorphisms and are subject to covariant section constraints.
The bosonic fields include an `internal' dreibein and an E$_{8(8)}$-valued
`zweihundertachtundvierzigbein' (248-bein). Crucially, the theory also features
gauge vectors for the E$_{8(8)}$ E-bracket governing the generalized
diffeomorphism algebra and covariantly constrained gauge vectors for a separate
but constrained E$_{8(8)}$ gauge symmetry. The complete bosonic theory, with a
novel Chern-Simons term for the gauge vectors, is uniquely determined by gauge
invariance under internal and external generalized diffeomorphisms. The theory
consistently comprises components of the dual graviton encoded in the 248-bein.
Upon picking particular solutions of the constraints the theory reduces to D=11
or type IIB supergravity, for which the dual graviton becomes pure gauge. This
resolves the dual graviton problem, as we discuss in detail.
