\documentclass[10pt]{article}
\usepackage{tikz}
\usetikzlibrary{backgrounds,fit,decorations.pathreplacing, intersections,
fadings, positioning} % TikZ libraries
\begin{tikzpicture}[remember picture,overlay]
\node(picA)[xshift=-2cm,yshift=-2cm, label=-90:Caption1] at (current
page.center){%
{\includegraphics[width=2cm]{photo.png}}};
\node(picB)[xshift=4cm,label=-90:Caption2] at (picA.center){%
{\includegraphics[width=2cm]{photo.png}}};
\node(picB)[yshift=4cm,label=-90:Caption3] at (picA.center){%
{\includegraphics[width=2cm]{photo.png}}};
\node(picB)[xshift=4cm, yshift=4cm,label=-90:Caption4] at (picA.center){%
{\includegraphics[width=2cm]{photo.png}}};
\node(picB)[xshift=2cm, yshift=2cm] at (picA.center){%
{\includegraphics[width=2cm]{photo.png}}};
\end{tikzpicture}
\end{document}