Church of the Holy Cross (Croatian: Crkva svetog Križa) is a Croatian Pre-Romanesque Catholic church originating from the 9th century in Nin.

[1] According to a theory from an art historian Mladen Pejaković,[2] the design has an intentionally unbalanced elliptical form designated to "follow" the position of the Sun, retaining the functionality of a calendar and sundial.

[2] In its beginning, in the time of the Croatian principality, it was used as a royal chapel of the duke's courtyard nearby.

[2] The church is that of a central type, it features the Croatian interlace (or simply "troplet") and a carved name of the župan of Nin "Godečaj".

[2][3] The church is known under the moniker of "the smallest cathedral in the world",[1][4][5] however it currently is not seat of a bishop of Nin.