  Superstring theory on ${\rm AdS}_3\times {\rm S}^3\times \mathbb{T}^4$ with
the smallest amount of NS-NS flux (`$k=1$') is shown to be dual to the
spacetime CFT given by the large $N$ limit of the free symmetric product
orbifold $\mathrm{Sym}^N(\mathbb{T}^4)$. To define the worldsheet theory at
$k=1$, we employ the hybrid formalism in which the ${\rm AdS}_3\times {\rm
S}^3$ part is described by the $\mathfrak{psu}(1,1|2)_1$ WZW model (which is
well defined). Unlike the case for $k\geq2$, it turns out that the string
spectrum at $k=1$ does {\it not} exhibit the long string continuum, and
perfectly matches with the large $N$ limit of the symmetric product. We also
demonstrate that the fusion rules of the symmetric orbifold are reproduced from
the worldsheet perspective. Our proposal therefore affords a tractable
worldsheet description of a tensionless limit in string theory, for which the
dual CFT is also explicitly known.
