Firefighters were called to the blaze at about 11:29 with roads around the building closed.
Emergency crews are dealing with a fire in the former Jenners department store in Edinburgh.
A Scottish Fire and Rescue Service spokesman said it responded to reports of a fire to the rear of the empty building on Rose Street at about 11:29.
No casualties have been reported but at least 10 fire engines are in attendance at the incident which has closed neighbouring roads.
The fire service said that on arrival crews found the building well alight.
Eyewitnesses have described smoke pouring out of the basement area of the department store.
The police cordon was later extended to cover the whole of St Andrew Square.
Staff from nearby offices have been evacuated.
Big fire behind Jenners #Edinburgh pic.twitter.com/GT1X1sBpaN
— Whacko™️🏴 (@Whacko1875)
The Jenners building is one the most iconic buildings on Edinburgh’s Princes Street.
Founded in 1838, it was one of the oldest department stores in the world until it closed.
It has been undergoing restoration due to take four years. Under the plan, about 10,000m2 of disused rooms in the six-storey building are due to be made into a hotel.
The current building was designed by architect William Hamilton Beattie in the Victorian renaissance revival style and opened in 1895 – after the original building was destroyed by fire in 1892.
The building was sold to private investors in 2005 after House of Fraser bought the Jenners brand and property.
It was then bought by Danish billionaire Anders Holch Povlsen in 2017 for a reported £53m.