It depends on what you are looking for. If you are looking for the classical Medieval city planning the I would recommend looking at feudal cities that were found across North-Western Europe such as France, Germany, and England. If you are looking for a Renaissance city, your best bet would either to look at the beginning of urbanization in Europe or some Italian cities. Rome is a very interesting city to look at since it has gone through various stages however Italy's planning is very different from the rest of Europe when it comes to the Middle Ages. If you want to look at the planning of a "perfect city" I would look at the planning of Pienza as it was created by Pope Pius II at the time to be a model Renaissance city. If you wanted to see the transition from Medieval to Renaissance outside of Italy, Paris and London both underwent very interesting changes throughout the 1600-1700s. Especially after the fire in London in 1666 there were some very interesting changes that happened to the city and how they went about planning their "perfect city".