Dellys (Arabic: دلّس, Berber: Delles) is a small Mediterranean town in northern Algeria's coastal Boumerdès Province, almost due north of Tizi-Ouzou and just east of the Sebaou River.

It is notable for its Ottoman-era Casbah, two colonial-era lighthouses (marking Cape Bengut), and some beaches; the principal activities of the area are fishing and farming.

During the colonial period the town grew southwards, as the port was expanded; a technical school, the École des arts et métiers, was also built to the north, near the cemetery.

To the south, former agricultural areas on the mountain slopes were built up with apartment buildings to form the new suburb Nouvelle-Ville, still surrounded by farmland on both sides.

To the west, the relatively level Ladjenna (or "Les Jardins") area, with rocky coasts, consisted mainly of family gardens and small farms until the mid-twentieth century, but is now largely built up.

It includes the tiny fishing port of El-Kouss; Cape Bengut, the northernmost land in the region, marked by a larger lighthouse; and the rock promontory of Sid El-Medjni.

[5] In addition to its seat, Dellys proper, the Dellys District is composed of the following localities: Ain Salem, Takdempt, Sidi El Medjni, Ladjenna, Bordj Fnar, Beni Azeroual, L'Assouaf, Lemchachka, Thouabet, Boukmach, Bouafia, Brarat, Dar El Melh (Les Salines), Boumedas, Ouled Mahdjoub, Beni Amara, Tizeghouine, Dar Rabah, Ouled Sabeur, Chegga, Mezoudj, Houasna, Azrou, Afir, Amadhi, Thissira, Ifri Tamarth, Ivehlal (Bhalil), Thala Ayache, Thala Arousse, El Marssa Tofaha.

Rusuccuru became part of the Roman Empire about 42 CE with Claudius' annexation of the Kingdom of Mauretania, and was subsequently promoted to the rank of municipium after the suppression of Aedemon's revolt.

With the arrival of Oruç and Hayreddin Barbarossa in the 16th century, Dellys became part of the Ottoman Empire; they initially made the town their eastern headquarters.

In the same year, French expansion was temporarily put on hold by the Treaty of Tafna, in which France recognized Emir Abdelkader's authority over most of western Algeria.

Areas east of Algiers, including Dellys, soon swore allegiance to Emir Abdelkader, who appointed Ahmed bin Salem to lead the district.

In 1839 Emir Abdelkader visited Dellys in person as part of a tour of his eastern frontiers, urging the inhabitants to prepare themselves for war rather than to place their trust in saints' tombs.

[17] In the wake of the revolt's failure, much of the agricultural land surrounding Dellys was confiscated and given to French settlers, notably at Sidi Daoud and Baghlia.

This commune saw the creation of several clandestine torture centers during the Algerian revolution: Algeria became independent in 1962; during the following decades, the town grew substantially.