Fort Frederick William, Military fort in Kędzierzyn-Koźle, Poland

Fort Frederick William, also known as Fort Rondel, is a circular four-story brick tower with an open circular courtyard at its center. Its outer circumference is 33.9 meters and the inner circumference is 15.6 meters. It stands on the right bank of the Oder in the Koźle district of Kędzierzyn-Koźle, in the Racibórz Basin of Opole Voivodeship, Upper Silesia.

The fort was built in 1805 to a design by the French military engineer Marc-René de Montalembert, but it was never completed. After the Koźle fortress was dissolved in the early 20th century, the fort was decommissioned and a malt house was set up in it. In 1945 it partly burned down and became a ruin.

The fort reflects French military engineering principles developed by Marc René de Montalembert, who focused on positioning artillery strategically for maximum defensive impact. This design philosophy shaped how such structures were built across Europe during the early 19th century.

The fort stands on the right bank of the Oder in the Koźle district of Kędzierzyn-Koźle. It can be visited only with a guide, so arrange a tour in advance before travelling there.

The fort was never completed: construction began in 1805 to a design by Marc-René de Montalembert, who died in 1800, and the work stopped unfinished. In the early 20th century the site was used as a malthouse, and in 1945 it partly burned and became a ruin.