Part of a Column from the Temple of Mentuhotep II

Part of an Octagonal Column from the Temple of Mentuhotep II at Deir el-Bahri
Dynasty 11, reign of Mentuhotep II (ca. 2051-2000 BCE)
Painted Limestone
From Thebes, Deir el-Bahri, Egypt Exploration Fund excavations, 1906-07
Gift of Egypt Exploration Fund, 1907 (07.230.5a,b)

(From info card):
"The columns of the temple's interior halls were each carved from a single piece of dark gray sandstone quarried in the region of Aswan. On its white-washed sides, the name of the king in his capacity as an incorporation of the god Horus was incised. It translates: 'The one who unites the two lands.'"

We can see the 'sema' or 'union' hieroglyph:

More about this here, (illustration Wilkinson)