The Samara Flag is a tricolor design (red, white, blue) with embroidery of the Mother of God of Iver, an icon from Eastern Orthodox Christian tradition. It was worn by nuns and Bulgarian volunteers in the Russo-Turkish War of 1877–78, gaining wider popularity after it avoided capture at the battle and massacre in Stara Zagora.

This monument is a towering, brutalist concrete replica of the flag, complete with tiled motifs in similar black and gold colors. While I wasn't able to find an angle that made this monument a literal flag shape, certain angles do play with negative space, creating the + symbol from the original flag, with the tall concrete pillar of the monument representing a flagpole.

Around the memorial grounds, the flag's motif can also be seen cast into beautiful metal plate tiles. Joining the concrete flag are seven huge busts atop other concrete pillars, symbolizing the six Bulgarian squads that entered battle under Russian command flighting for freedom from the Ottomans.

Translation:

"Centuries have passed since the last time Bulgarian flags flew in the ranks of the free Bulgarian companies. Those flags sank in rivers of blood on Kosovo Field and now the native flag rises again over the Bulgarian companies. From afar, across the whole Russian land, it has been brought by us for you, as living proof that it is given to you not from some corner of Russia, but from the whole Russian land."

From the speech of P. Va. Alabin upon the return of the Samara flag
– May 6/18, 1877, Pleven