  It is a well-known fact, that the greatest ambit for a topological group $G$
is the Samuel compactification of $G$ with respect to the right uniformity on
$G.$ We apply the original destription by Samuel from 1948 to give a simple
computation of the universal minimal flow for groups of automorphisms of
uncountable structures using Fra\"iss\'e theory and Ramsey theory. This work
generalizes some of the known results about countable structures.
