/usr/lib/x86_64-linux-gnu/libcitygml.so is in libcitygml0-dev 0.14+svn128-1+3p0p1+4.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libcitygml.so.0
/usr/lib/x86_64-linux-gnu/libcitygml.so.0