Sioni was originally built in the 6th and 7th centuries, but has been destroyed and rebuilt many times, and what you see today is mainly 13th century. It is of special significance for Georgians because it's home to the sacred cross of St Nino which, according to legend, is made from vine branches bound with the saint’s own hair. A replica of the cross sits behind a bronze grille to the left of the icon screen. The real thing is apparently kept safe inside.