  Global Positioning System (GPS) dissemination of frequency standards is
ubiquitous at present, providing the most widespread time and frequency
reference for the majority of industrial and research applications worldwide.
On the other hand, the ultimate limits of the GPS presently curb further
advances in high-precision, scientific and industrial applications relying on
this dissemination scheme. Here, we demonstrate that these limits can be
reliably overcome even in laboratories without a local atomic clock by
replacing the GPS with a 642-km-long optical fiber link to a remote primary
caesium frequency standard. Through this configuration we stably address the
$^1$S$_0$---$^3$P$_0$ clock transition in an ultracold gas of $^{173}$Yb, with
a precision that exceeds the possibilities of a GPS-based measurement,
dismissing the need for a local clock infrastructure to perform high-precision
tasks beyond GPS limit. We also report an improvement of two orders of
magnitude in the accuracy on the transition frequency reported in literature.
