The Church of the Holy Cross called „the smallest cathedral in the world“ is the most valuable preserved monument of early Croatian religious architecture and one of Nin's symbols. By its position and beauty it dominates the area where it stands. It was built in the 9th century, in the Early Christian period. It is the only religious object in Nin which has remained untouched since its construction to date. It is 7.80 m long, 7.60 m wide, and 8.20 metres in height (inside measures) and the walls are 57cms thick. It was built on the remains of ancient houses which are visible even today. During the reign of Croatian Kings it served as a Court chapel for the nearby Duke's Court. A number of medieval graves were discovered around the church.
This small church, thanks to the position of its windows and the angle of the fall of light is a kind of calendar, and according to the sun 's rays, the exact date of the equinox and solstice can be determined, which on the first day of summer is the start of an interesting event called „The Festival of Sun and Light“.
Spellbound by its beauty, the famous English architect Thomas Jackson, called it „the smallest cathedral in the world“.