documentclass[slidestop,compress,11pt,xcolor=dvipsnames]{beamer}

definecolor{LHCblue}{RGB}{4, 114, 255}
usecolortheme[named=LHCblue]{structure}
usepackage[bars]{beamerthemetree} % Beamer theme v 2.2
usepackage{multicol}
usepackage{lmodern}

usepackage{marvosym}

begin{document}

begin{frame}
begin{columns}[t]
column{.5textwidth}
centering
includegraphics[width=5cm,height=3.5cm]{example-image-golden}\
includegraphics[width=5cm,height=4cm]{example-image-golden}
column{.5textwidth}
centering
includegraphics[width=5cm,height=4cm]{example-image-golden}\
includegraphics[width=5cm,height=4cm]{example-image-golden}
end{columns}
end{frame}