As another picture shows this monument is on a square with the mosque in sight, Osman Gazi refers to Osman I, the first Sultan of the Ottoman Empire. Konuralp Bey, one of Osman Gazi's commanders, was ordered to conquer Düzce and its surroundings to the Ottoman lands. In the 14th century he captured Duzbazaar (Düzce) and Roman Prusias after a battle against the Byzantines. Düzce is the province Akçakoca belongs to.

This highly irregular mosque was placed above 160 concrete poles driven into the ground. The dome height is 31 meters and covered by 32 tons of copper plates. And the chandelier that resembles the dome in reverse weigh around 1300 kg. The rocket like minarets are at 58 meters in height. The main inspiration of the dome is from the tents which were being used by the Turkic people in the steppes of the Central Asia, and eight large stain-glass-windows adorn this unique dome.
Some pictures show the exterior, some the interior, I think no further explanation is in order.