The occasion is French President Emmanuel Macron’s final visit to the construction site to see the restoration for himself before the famous monument’s reopening for worship on December 8.
His two-hour tour is being televised live.
The images are expected to be breathtaking, showing renovated stonework, vibrant colours, and other fruits of the mammoth reconstruction.
Joined by artisans, architects, business leaders and donors, Mr Macron is expected to pay tribute to the craftsmanship and dedication of all those who worked to bring Notre Dame back to life.
The visit kicks off a series of events ushering in the reopening of the 12th-century Gothic masterpiece.
Mr Macron will return on December 7 to deliver an address and attend the consecration of the new altar during a solemn Mass the following day.
Mr Macron’s administration is hailing the reconstruction as a symbol of national unity.