  It is well-known that an integrally closed domain $D$ can be express as the
intersection of its valuation overrings but, if $D$ is not a Pr\"{u}fer domain,
the most of valuation overrings of $D$ cannot be seen as localizations of $D$.
The Kronecker function ring of $D$ is a classical construction of a Pr\"{u}fer
domain which is an overring of $D[t]$, and its localizations at prime ideals
are of the form $V(t)$ where $V$ runs through the valuation overrings of $D$.
This fact can be generalized to arbitrary integral domains by expressing them
as intersections of overrings which admit a unique minimal overring. In this
article we first continue the study of rings admitting a unique minimal
overring extending known results obtained in the 70's and constructing examples
where the integral closure is very far from being a valuation domain. Then we
extend the definition of Kronecker function ring to the non-integrally closed
setting by studying intersections of Nagata rings of the form $A(t)$ for $A$ an
integral domain admitting a unique minimal overring.
