The left central portion of the lintel,
(the photo has been rotated 90 degrees clockwise to make viewing easier).
There were a series of what looks like twig rune carvings across the whole width
of the area marked by the blue rectangle.
Modern graffiti has destroyed or obscured most of this inscription, but two of
the runes can still be made out on the left with dark
patination in their grooves.
The same area photographed using low angle
illumination from two different directions.
This method reveals the remaining grooves of the original carving which are
deeper and more sharply incised than the graffiti overlaying them.