As used in this act:
"State property" means land and improvements owned by the State and includes but shall not be limited to State offices, hospitals, institutions, schools, colleges, universities, garages, inspection stations, warehouses, barracks and armories together with abutting vacant land held for future development for the same purposes. State property shall not include that used or held for future use for highway, bridge or tunnel purposes or property which is qualified under State law for any other State payment in lieu of taxes.