The old town of Fredrikstad was founded in 1567 after the previous settlement of Borg had been burned to the ground by Swedish forces during the Northern Seven Years' War. The new location was chosen to make it easier to defend it, though the Swedes succeeded in burning down the fledgling town in the 1570s. The construction of the fortifications, including a moat and ramparts, began in the 1660s. The fortified town began to lose influence to new settlements on the opposite side of the river already in the 18th century, and the city administration and cathedral was finally moved at the end of the following century. Apart from some military buildings, The oldest houses are from after the fire of 1764 while several parts of town were also rebuilt after a fire in 1830. Some minor fires and rebuilding later in the century also added some later housing stock, though the town otherwise became frozen in time.
The borough on the opposite side of the river to the old town is named Cicignon after a fort built in the late 17th century. Demolition of the fort began in 1903 and a the villas at the end of J.N. Jacobsens gate have been dated to the same year. One of the brick mansions later became the residence of the bishop of the diocese of Borg.
The main church of Fredrikstad was built in 1879-80 to a design by master mason Waldemar Ferdinand Luhr. It was previously called Vestre Fredrikstad kirke to distinguish it from the church in the old town. It has been a cathedral since 1969, when the diocese of Borg was created.
Litteraturhuset was completed in 2013 to a design by architect Griff Arkitektur. The building houses a bookshop, book café and an institute of journalism. On the right can be seen a commercial building from 1903-04, originally built for Fredrikstad og Omegn sparebank, by architect Gustav Lorentz Gulbrandsen.