Porolissum was an ancient Roman city in Dacia, a region that is part of modern Romania. Established as a military camp in 106 during Trajan's Dacian Wars, the city quickly grew through trade with the native Dacians and became the capital of the province Dacia Porolissensis in 124. The site is one of the largest and best-preserved archaeological sites in Romania. It is 8 km away from the modern city of Zalău, in Jac village, Creaca Commune, Sălaj County.

Porolissum in Gunpowder Empire[]

In one alternate, known as "Agrippan Rome," Polisso was a city in the Roman province of Dacia. The equivalent home timeline location was the ruined city of Porolissum in Romania.

Crosstime Traffic sent traders to Polisso, trading low-tech items like watches and pocket knives for food, including grain.

In the late 21st Century, the city's prefect was Sesto Capurnio.

Crosstime agents John and Melissa Solters, accompanied by their teenage children Jeremy and Amanda, arrived in Polisso on a routine trading mission. While there, Melissa was stricken with appendicitis and had to be moved to the home timeline for treatment. As John accompanied her, the teens were left on their own for the time being, which extended indefinitely when a terrorist attack in Romania left the Crosstime portal impassable.

During this time, the Roman Empire and the Lietuvan Empire declared one of their periodic wars against each other. Polisso, being near the border, was attacked by the Lietuvan army. One of the invading soldiers entered the Solters office and was wounded by Jeremy. Eventually, the Romans drove the Lietuvans out and retook the city.