Defining << operator at a base class - c++

Question

I'm trying to define the << operator for a base class, so I can later print the identifier of each object easily.
I have tried an SSCCE, but I don't really know where the problem is, since I'm printing a direction and not the content. I don't know if the problem appears by printing the vector position, or by printing the std::string(char[]).
main.cpp:
#include "City.h"
#include <vector>
#include <iostream>
int main() {
std::vector<Location*> locations;
locations.push_back(new City("TEST"));
for(unsigned int it = 0; it<locations.size(); it++){
std::cout << locations[it] << std::endl;
}
return 0;
}
Location.h:
#include <cstring>
#include <string>
class Location {
public:
Location(const std::string id);
friend std::ostream& operator<<(std::ostream& os, Location& loc);
std::string GetId();
private:
// Name/identifier of the location
char ID[5];
};
Location.cpp:
#include "Location.h"
Location::Location(const std::string id){
memset(this->ID, 0, 5);
strncpy(this->ID, id.c_str(), 5); // I have it as a char[5] at a larger app
}
std::string Location::GetId(){
return std::string(this->ID);
}
std::ostream& operator<<(std::ostream& os, Location& loc){
os << loc.GetId();
return os;
}
City.h:
#include "Location.h"
class City: public Location{
public:
City(std::string id);
};
City.cpp:
#include "City.h"
City::City(const std::string id) : Location(id){
}
Any idea?