The Great Al-Omari Mosque is one of the oldest and most prominent mosques in the Gaza Strip. It is located in the heart of Old Gaza, in the Al-Daraj neighborhood. It was established during the era of Caliph Omar Ibn Al-Khattab and is considered the third largest mosque in Palestine.

The oldest section of the mosque was constructed in the basilica style of the Cathedral of Saint John the Baptist in the 12th century AD. It is believed that the mosque was built on the site of the Temple of the god Marna during the Roman period, as well as the Byzantine Church of Eudoxia. The mosque is notable for its inscriptions dating back to the Mamluk and Ottoman eras.

It was named "Al-Omari" in reference to Caliph Omar Ibn Al-Khattab, and "Great" because it is the largest mosque in the Gaza Strip, covering an area of approximately 4,100 square meters. Inside, it houses a library containing numerous historical books and manuscripts. The mosque was built from Kurkar sandstone, and its outer courtyard is adorned with decorations and circular arches. The structure reflects the style of ancient architecture, surrounded by circular arches and centered with elevated domes. It has five gates that open to historic streets and alleyways bearing the legacy of the civilizations that once inhabited Gaza City.

The mosque is distinguished by its towering minaret, adorned with diverse Mamluk-style decorations. The minaret is square-shaped in its lower half and octagonal in its upper half, which consists of four levels.

The mosque was subjected to bombardment by Israeli occupation aircraft, resulting in partial destruction during the aggression on the Gaza Strip. Israel had previously destroyed parts of the mosque during its war on Gaza in 2014.