It seems that Mono.Cecil is part of mono-core, even though there is a specific package for it (https://admin.fedoraproject.org/pkgdb/package/rpms/mono-cecil/). to test: rpm -ql mono-core | grep Cecil /usr/lib/mono/gac/Mono.Cecil /usr/lib/mono/gac/Mono.Cecil/0.9.5.0__0738eb9f132ed756 /usr/lib/mono/gac/Mono.Cecil/0.9.5.0__0738eb9f132ed756/Mono.Cecil.dll /usr/lib/mono/gac/Mono.Cecil/0.9.5.0__0738eb9f132ed756/Mono.Cecil.dll.mdb in mono-cecil package: rpm -ql mono-cecil | grep Mono.Cecil.dll /usr/lib/mono/Mono.Cecil/Mono.Cecil.dll /usr/lib/mono/gac/Mono.Cecil/0.9.6.0__0738eb9f132ed756/Mono.Cecil.dll /usr/lib/mono/gac/Mono.Cecil/0.9.6.0__0738eb9f132ed756/Mono.Cecil.dll.mdb it seems, Mono.Cecil is in the mono tarball, in the external directory. see also https://github.com/mono/mono/blob/master/mcs/class/Mono.Cecil/Mono.Cecil.dll.sources
when building nunit 3.4, I need the newer version of Mono.Cecil, to avoid compiler error: Type `Mono.Cecil.ModuleDefinition' does not contain a definition for `RuntimeVersion'