Barda Tower Mausoleum, Medieval mausoleum in Barda, Azerbaijan.

Barda Tower Mausoleum is a cylindrical brick tower about 14 meters high and 10 meters in diameter, its surface clad in glazed blue-green bricks set vertically against horizontal red bricks to repeat the word "Allah" over 200 times. Two portals face north and south; the northern one projects 30 cm and is more richly decorated. Inside, the ground chamber shifts from a circle to a ten-sided prism with arched niches, while the underground burial vault is cross-shaped.

Built in 1322, as recorded in a inscription on the south portal giving the date Shawwal 722 AH, the mausoleum's north portal names its architect: Ahmad, son of Hafiz Eyyub, of Nakhchivan. The orientalist Boris Dorn described the monument in 1861 and published a drawing, predicting its destruction by locals taking bricks from its base. After Sovietization the tombstones were destroyed and Arabic inscriptions erased; restoration ran from 2012 to 2018.

The turquoise-glazed and red bricks of the cylindrical shaft are laid vertically and horizontally so that the word "Allah" repeats more than 200 times across the facade, set at a 45-degree angle. A wide band of Kufic inscription runs around the upper frieze, and the name of the builder, Ahmad son of Hafiz Eyyub of Nakhchivan, is recorded on the north portal.

The mausoleum has two entrances aligned north–south; the northern one is the burial chamber's only door, reached by a stepped dromos. The northern portal projects 30 cm from the tower and is the richer of the two. The upper chamber is a ten-sided room with arched niches, and the restored stair to the crypt is covered with glass.

The interior of the mausoleum reveals a surprising geometric transformation: the cylindrical shape shifts into a ten-sided form about 2 meters up, then returns to circular at the top. This change is invisible from outside and surprises visitors when they step inside.