Crowds gathered in central Paris on Monday as French artist JR officially opened his latest large-scale installation, transforming the historic Pont Neuf bridge into a giant immersive cave.

Long queues formed outside the attraction as visitors entered the inflatable structure, which covers part of Paris' oldest bridge and is designed to create the sensation of walking through an underground cavern.

The installation combines sound effects, lighting and augmented reality features to immerse visitors in what JR describes as a sensory experience. The artist said the project is free to access and open 24 hours a day.

Many visitors described the attraction as unusual and highly immersive, praising its cave-like atmosphere and dramatic transformation of one of Paris' most famous landmarks.