Sure, why wouldn't they? It wasn't the only way cities could spring up, but a location beside a major roadway could certainly help a city or town grow. In this map of the first part of the Ancient Roman road Via Emilia, you can clearly see that towns spring up around bridges where the road intersects a river. In fact, this trend largely repeats along the length of the Emilia.

Observing medieval trade routes, you can see how cities like Verona and Milan are conveniently located at the intersection of north-south routes with east-west routes: Milan, for example, is located where the axis starting in Venice (at the head of the Eastern Mediterranean seafaring routes) drawn westward through the valleys of Aosta and Susa onward into France intersects with the axis drawn from Genoa (an entrepôt of Western Mediterranean trade) through the Telline valley into Germany.

Of course, Milan is a city with an ancient history, and was already settled by celtic peoples when it was first absorbed into the early Roman Empire. However, the city's growth compared to its neighbors, like Pavia and even Verona, is certainly attributable to its position at the intersection of important roadways.

In addition to where roads intersect rivers, and where roads intersect each other, towns could also spring up at the foot of mountain passes. Towns like Susa and Aosta lie at the gateway to important routes over the Western Alps. Verona is similarly at the base of the river Adige's valley, which leads to the Brenner Pass over the mountains. Higher up in the mountains, small communities could also spring up atop the passes themselves! The St. Bernard Monastery in Switzerland is a famous example, however there are countless others, religious and non-religious alike. In fact, one of the earliest documents mentioning the famous Medici dynasty of Florence is a thirteenth-century donation to the Camaldoli Monastery, overlooking a route over the Appenines into the Medici's ancestral estates.