Cleanning code. Found simpler maps at http://code.highcharts.com/mapdata/. Removed the city class.

city.cpp

-#include "city.h"
-
-void City::pushPoint(double x, double y) {
-    geometry->push_back(QPointF(x,y));
-
-}

city.h

-#ifndef CITY_H
-#define CITY_H
-
-#include <QPointF>
-#include <QVector>
-
-///
-/// \brief The City class
-///        This is merely a vector of points, i.e. the points that make up the
-///        polygon of the city.
-
-class City {
-public:
-    QVector<QPointF> *geometry;
-    
-    /// \fn City()
-    /// \~English
-    /// \brief default constructor
-    /// \~Spanish
-    /// \brief default constructor
-    ///
-    City() {};
-
-    /// \fn pushPoint(double x, double y)
-    /// \~English
-    /// \brief push a point to the vector of points
-    /// \~Spanish
-    /// \brief añadir un punto al final del vector de puntos
-    ///
-    void pushPoint(double x, double y);
-
-    /// \fn getSize()
-    /// \~English
-    /// \brief get the size of the vector that contains the points
-    /// \~Spanish
-    /// \brief devuelve el tamaño del vector de puntos
-    ///
-    virtual int getSize() const { return geometry->size(); }
-
-    /// \fn QVector<QPointF> *getGeometry()
-    /// \~English
-    /// \brief get a pointer to the vector of points
-    /// \~Spanish
-    /// \brief devuelve un puntero al vector de puntos
-    ///
-    QVector<QPointF> *getGeometry() const { return geometry; }
-    
-
-    /// \fn ~City()
-    /// \~English
-    /// \brief destructor
-    /// \~Spanish
-    /// \brief destructor
-    ///    
-    ~City() {delete geometry; }
-};
-
-#endif // CITY_H

country.cpp

 #include <QJsonDocument>
 
 void Country::limits(){
-    QMap<QString,City*>::iterator it = Cities.begin();
+    QMap<QString,QPolygonF*>::iterator it = Cities.begin();
 
-    minX = maxX = Cities.begin().value()->geometry->at(0).x();
-    minY = maxY = Cities.begin().value()->geometry->at(0).y();
+    minX = maxX = Cities.begin().value()->at(0).x();
+    minY = maxY = Cities.begin().value()->at(0).y();
 
     for (it = Cities.begin() + 1; it != Cities.end(); ++it) {
 
-        City *c = it.value();
+        QPolygonF *c = it.value();
 
-        for (int i = 0; i < c->getSize(); i++) {
-            if (c->geometry->at(i).x() != 0.0) {
-            if (c->geometry->at(i).x() > maxX ) maxX = c->geometry->at(i).x();
-            if (c->geometry->at(i).y() > maxY ) maxY = c->geometry->at(i).y();
-            if (c->geometry->at(i).x() < minX ) minX = c->geometry->at(i).x();
-            if (c->geometry->at(i).y() < minY ) minY = c->geometry->at(i).y();
+        for (int i = 0; i < c->size(); i++) {
+            if (c->at(i).x() != 0.0) {
+            if (c->at(i).x() > maxX ) maxX = c->at(i).x();
+            if (c->at(i).y() > maxY ) maxY = c->at(i).y();
+            if (c->at(i).x() < minX ) minX = c->at(i).x();
+            if (c->at(i).y() < minY ) minY = c->at(i).y();
             }
         }
     }
     QFile loadFile(fileName);
 
     if (!loadFile.open(QIODevice::ReadOnly)) {
-        qWarning("Couldn't open save file.");
+        qWarning("Couldn't open read file.");
         return false;
     }
 
+    qDebug() << "JSON ok...";
+
     QByteArray saveData = loadFile.readAll();
     QJsonDocument loadDoc(QJsonDocument::fromJson(saveData));
-    QJsonArray topLevelArray = loadDoc.array();
 
+    QJsonArray featureLevelArray = loadDoc.object()["features"].toArray();
     int ctr = 1;
-    foreach(QJsonValue obj, topLevelArray) {
-        QVector<QPointF> *points = new QVector<QPointF>;
+    foreach(QJsonValue obj, featureLevelArray) {
+        QPolygonF *poly = new QPolygonF;
         QJsonArray geometryArray = obj.toObject()["geometry"].toObject()["coordinates"].toArray();
         QString polyType = obj.toObject()["geometry"].toObject()["type"].toString();
+        qDebug() << polyType;
         if (polyType == "Polygon") {
             for (int i = 0; i < geometryArray[0].toArray().size(); i++) {
-                points->push_back(QPointF(
+                poly->push_back(QPointF(
                                 geometryArray[0].toArray()[i].toArray()[0].toDouble(),
                                 geometryArray[0].toArray()[i].toArray()[1].toDouble()));
             }
             for (int i = 0; i <geometryArray.size() ; i++) {
                 // for every point in the city's polygon
                 for (int j = 0; j < geometryArray[i].toArray()[0].toArray().size(); j++) {
-                    points->push_back(QPointF(
+                    poly->push_back(QPointF(
                                           geometryArray[i].toArray()[0].toArray()[j].toArray()[0].toDouble(),
                                           geometryArray[i].toArray()[0].toArray()[j].toArray()[1].toDouble()));
 
                 }
                 // I will push a 0,0 between each polygon of a multipolygon to distinguish
-                points->push_back(QPointF(0,0));
+                poly->push_back(QPointF(0,0));
             }
         }
 
-        QString cityName = obj.toObject()["properties"].toObject()["city"].toString();
+        QString cityName = obj.toObject()["properties"].toObject()["name"].toString();
 
         qDebug() << "Storing: " << cityName;
-        Cities[cityName] = new City;
-        Cities[cityName]->geometry = points;
+        Cities[cityName] = poly; //new City;
+        //Cities[cityName]->geometry = poly;
 
         ctr++;
     }

country.h

 #define COUNTRY_H
 
 #include <QPointF>
-#include <city.h>
 #include <QMap>
-
+#include <QPolygonF>
 
 /// \brief A class to display a map of a country, given the coordinates
 /// that define its limits.
 class Country {
 private:
 public:
-    QMap<QString,City*> Cities;
+    QMap<QString,QPolygonF*> Cities;
     double minX, minY, maxX, maxY;
 
     /// \fn Country()
 
 };
 
+
 #endif // COUNTRY_H

mainwindow.cpp

 #include "mainwindow.h"
 #include "ui_mainwindow.h"
-#include <QPainter>
-#include <QPen>
-#include <QCoreApplication>
-//#include <QJsonDocument>
-#include <QFile>
 #include <QDebug>
-//#include <QJsonArray>
-//#include <QJsonObject>
-#include <QDesktopWidget>
-#include <QVector>
-#include <QPoint>
-#include <string>
-#include <QPolygon>
-#include <city.h>
 #include <country.h>
-#include <QPointF>
 #include <gispoi.h>
 
 using namespace std;

map.cpp

     srand(time(NULL));
 
     // Create country object and read data from the json file
-    myCountry = new Country;  
-    myCountry->readInfoFromJSON(":/data/cityLimitsPR.json");
+    qDebug() << "Reading the Json...";
+    myCountry = new Country;
+    myCountry->readInfoFromJSON(":/data/pr-all-all.geo.json");
+    qDebug() << "...done, read " << myCountry->Cities.size();
+
 
     cityColorMap = NULL;
     gisLocations = NULL;
 
 
     int colorCtr = 0;
-    QMap<QString,City*>::iterator it;
+    QMap<QString,QPolygonF*>::iterator it;
     unsigned int randColor;
     int cityCounter = 0;
 
     for (it = myCountry->Cities.begin() ; it != myCountry->Cities.end(); ++it) {
-        City *c = it.value();
+        QPolygonF *c = it.value();
 
         int x1 ,y1, x2, y2;
-        x1 = factorX * (c->getGeometry()->at(0).x() - myCountry->minX);
-        y1 = height() - factorY*(c->getGeometry()->at(0).y() - myCountry->minY)  ;
+        x1 = factorX * (c->at(0).x() - myCountry->minX);
+        y1 = height() - factorY*(c->at(0).y() - myCountry->minY)  ;
 
-        QPointF p1 = c->getGeometry()->at(0);
+        QPointF p1 = c->at(0);
         QPointF p2;
         int ctr = 0;
 
 
 
 
-        for(int i = 0; i < c->getSize() + 1; i++) {
-            p2 = c->getGeometry()->at((i+1)%c->getSize());
+        for(int i = 0; i < c->size() + 1; i++) {
+            p2 = c->at((i+1)%c->size());
 
             x2 = factorX * (p2.x() - myCountry->minX);
             y2 = height() - factorY*(p2.y() - myCountry->minY)  ;

prMap.pro

 
 SOURCES += main.cpp\
         mainwindow.cpp \
-    city.cpp \
     country.cpp \
     map.cpp \
     gispoi.cpp
 
 HEADERS  += mainwindow.h \
-    city.h \
     country.h \
     map.h \
     gispoi.h
 RESOURCES += \
     prmap.qrc
 
-DEFINES += QT_NO_DEBUG_OUTPUT
+#DEFINES += QT_NO_DEBUG_OUTPUT

prmap.qrc

 <RCC>
     <qresource prefix="/">
-        <file>data/cityLimitsPR.json</file>
+        <file>data/pr-all-all.geo.json</file>
     </qresource>
 </RCC>