Clay Unto Worlds
If there is a thing for which dwarves are best known, it is their skill with engineering. The underways that they maintain between their fortress cities provide safe, reliable (if rather monotonous) travel, and those selfsame fortress cities are all but impervious to the most determined siege. Of course, there is far more to the dwarves than this, but this is what is most visible to the world, and what they have proven to excel at beyond the skill of all others.
The dwarven underways are a massive network of roads, completely encased in the rock that underlies the world. In those places where the underways intersect natural caverns, these caverns have been collapsed or walled off, using both physical and magical means to establish a boundary. The roads themselves are patrolled by dwarven caravans that act as security and maintenance, as well as offering assistance to travelers in need. Unfortunately the underways are also largely undecorated and quiet, while the engineering skills of the dwarves serve to make the road surfaces extremely level- resulting in a tremendous monotony. Of course, this means that caravans making long trips through the underways are excellent sources of employment for traveling minstrels and bards.
Dwarven society is an unusual mixture of practicality and piety; most dwarves are devout followers of the Allfather, though the other gods have their own smaller followings. Many people who are not familiar with dwarven customs find the dwarves to be remarkably tight-lipped about their faith, and rarely if ever worship publicly. However this is anything but accurate; the dwarven faith in the Allfather teaches that the act of creation is the act of worship, and in fact every dwarven feat of engineering is a monument to their god.