The land of Israel is an organic whole. It cannot be divided, anymore than a person can divide or remove parts of his body. And just as different parts of the body serve different functions, different parts of Israel also serve different spiritual purposes. The extremely diverse geographies of Israel correspond to the incredible variety of spiritual experiences with which all of us sometimes resonate. One way of seeing this clearly is by considering the twelve tribes of Israel. They originally divided up the land into twelve areas, and every tribe developed a personality that corresponded to the areas in which it was located.
After entering the land of Israel, the Jews developed the Chabad style of Jewish meditation. Before entering Israel, as they wandered in the desert, the Jews were so close to the original revelation at Sinai, that it was not necessary to meditate - the visual experience of receiving the Torah accompanied them as they journeyed and they did not have to meditate upon spiritual topics in order to be in contact with spirituality. But upon entering the land of Israel, it became important to exercise their faculties of Chabad in order to develop sensitivity to the spiritual message of Israel.
The same is true of our four holy cities. Each corresponds to a basic personality trait, rooted in the nature of the land as well as in the nature of the person. The most ancient Jewish city is Hevron, the city of "earth." Here, our forefathers and mothers are buried in the earth of the cave of Machpela. Earth in the soul can be our sense of being grounded and purposeful, but if we are not careful, earth can also impart the traits of indolence and depression, which we need to uproot.
Jerusalem is the city of "fire." Here was located the holy Temple, in which offerings were burned with fire, and in which intense spiritual experience was the "order of the day." This is true now as well, as Jerusalem is an intense city in which people take their spiritual experience with utmost seriousness. But, if we are not careful, the same fire may impart anger and arrogance, against which we must guard.
Tiberius, located on the large body of water, Lake Kineret, is the city of water. Water, or more generally, moisture, gives rise to all forms of physical pleasure. There is nothing wrong with physical pleasure within the boundaries permitted by the Torah. But, we must be careful not to enjoy physical pleasure in ways that are outside the realm of Torah.
And finally, there is Tzfat, the city of air. On the one hand, we need air to live. On the other hand, too much air makes us light-headed, giving way to the negative character traits of idle talk, scoffing and not using our time well. But, the right amount of air encourages us to search for the spiritual, mystical dimensions of Judaism, which is what the famous mystics of Tzfat (including the Ari z'l, greatest kabbalist of all times) did way back in the sixteenth century.
Then, there is a fifth holy city - Shechem. There were three times in Jewish history that the entire nation entered the land of Israel. The first time was when the patriarch Abraham entered the land from the north, coming from what is probably now Iraq. He entered at the area called Elon Moreh, or Shechem (commonly known as Nablus).
The second entrance was when the patriarch, Jacob, gathered his family and returned to Israel after twenty-two years of working for his father in law. He also entered at Elon Moreh/Shechem, but this time from the east.
And the final time that the Jews in their entirety entered the land was when Joshua led them into Israel after the exodus and forty years in the desert. This time, they came from the south, but again entered at Elon Moreh/Shechem. It was at this point that the Jews began to meditate using Chabad methods, exercising their faculties of chochma, bina and da'at.
There must be something special about this area that every time the entire Jewish people entered Israel, it was precisely here. One of the Chassidic masters (the "Shem miShmuel) explained that the sheer beauty of the area of Elon Moreh/Shechem imparts the personal traits of boldness and bravery to it dwellers. And the Jews entering their land certainly needed these traits, and this is why the One above led them there before all other locations in Israel.