In the book I’m currently writing, (Draugr’s Saga), I’m doing a lot of research on old viking longphorts, which were temporary fortifications built by Vikings while in foreign lands. A simple example is illustrated in the black and white sketch. Ostensibly they were built to overwinter, but many turned into permanent and profitable trading centers. Many of Irelands largest cities began as longphorts: Dublin, Waterford, Cork, and Limerick.
Here’s a description of the one in my story: (btw, Luimneach is Limerick). The color picture I added is a layout typical of a more permanent fortress that they would have evolved into. The one I describe below is four times that size.
The longphort had been built taking advantage of the southern tip of the island and the surrounding river to aid in its defense. They’d built a goodly portion of the walls right up to the edge of the river bank, which would make it very hard for an enemy to mass at those points. They would have to come inland from the northern half of the island, where presumably, the vikings had other traps and tricks prepared for would be besiegers.
In addition to the natural protection the river surrounding the longphort provided, Luimneach also boasted a ditch at least three yards deep—excepting the areas that fronted the river—and an accompanying earthen rampart just as high, on top of which, an imposing palisade loomed over visitors. The sight of it swelled Aedan’s heart. This was a magnificent viking fortress, every bit as glorious and formidable as Sigurd’s stories had lead him to believe. Stout timber guard towers flanked the entrance through a tunnel in the earthen rampart and palisade. Inside Luimneach’s defensive ring, a vast open-air market bustled with trade. Huts and shanties sprang up at random around the market. In the center of the expansive palisade, stood another ring—a second, concentric fortification, though less grand than the outer ring. It seemed this is where his escorts were leading him.
They passed through a gate, also flanked by two guard towers. Inside the second ring, clusters of four viking longhouses formed orderly squares, with a common area in between the four and streets in between the clusters of four. Aedan counted sixty-four longhouses in all. This must be where the Northmen lived. Aedan deduced that they must quarter the foreigners and slaves in the outer ring—their utgard. They’d still be protected while they traded, yet this offered the Northmen a safe place to fall back to in case the worse happened—a slave revolt, or a raid by locals.
Like Vadrefjord, Luimneach had proper streets, but instead of woven willow, the streets sported a layer of planed logs on top of gravel. Aedan had never seen a settlement so sophisticated. The odors of civilization still accosted his nose, though not quite as intensely as they had at Vadrefjord. Had they Roman plumbing perhaps? Wishful thinking he knew.