/usr/include/ImageMagick/ is in libmagick++-dev 8:6.6.9.7-5ubuntu3.9.
This file is owned by root:root, with mode 0o755.
..
/usr/include/ImageMagick/Magick++/
/usr/include/ImageMagick/Magick++.h
/usr/include/ImageMagick/Magick++/Blob.h
/usr/include/ImageMagick/Magick++/CoderInfo.h
/usr/include/ImageMagick/Magick++/Color.h
/usr/include/ImageMagick/Magick++/Drawable.h
/usr/include/ImageMagick/Magick++/Exception.h
/usr/include/ImageMagick/Magick++/Geometry.h
/usr/include/ImageMagick/Magick++/Image.h
/usr/include/ImageMagick/Magick++/Include.h
/usr/include/ImageMagick/Magick++/Montage.h
/usr/include/ImageMagick/Magick++/Pixels.h
/usr/include/ImageMagick/Magick++/STL.h
/usr/include/ImageMagick/Magick++/TypeMetric.h