Chapel of Our Lady of the Belfry, Catholic church in Split, Croatia.

The Chapel of Our Lady of the Belfry occupies a former guardhouse corridor above the Iron Gate in Diocletian's Palace, entered by high exterior stairs. Its interior was divided in the 11th century into three bays with cross vaults, and a pre-Romanesque bell tower rises above the central bay. The tower is the oldest preserved on the Croatian Adriatic coast.

The chapel originated in the 6th century as a guardhouse but was converted when refugees from nearby communities came seeking shelter. This transformation turned it into a religious site that has served the local population since.

The chapel is connected to a painted icon of Mary that long hung within the building and shaped the devotion of worshippers. The image was later moved to the treasury of Saint Dujam Cathedral and remains an important work from the religious art tradition of this region.

The chapel sits above the Porta Aurea (Iron Gate) on Bajamontijeva 1, reached by high exterior stairs from the gate passage; the interior is small and dim. The Croatian Conservation Institute has worked on the Iron Gate and chapel since 2013, with the second phase of restoration, costing HRK 800,000, renewing the bell tower roof timbers and the medieval fresco on the facade.

The bell tower ranks among the earliest such structures in Croatia and incorporates fragments of ancient altarpieces within Gothic windows. This combination of materials shows how earlier artistic works were preserved during later renovations.