A LAYER of black soot from years of traffic pollution has been wiped off one of Oxford’s most iconic buildings.

More than 25 professional workers helped to clean and repair the main Limestone facade of Oxford University’s Examination Schools building in High Street, where students sit their exams.

Spokesman Kay Hogg said: “The building is one of Oxford’s best kept secrets, which has been hidden behind dirt for a long time.

“The refurbishment brings the building back to the forefront of the city and makes it much more visible.”

Workers used high-pressure water hoses to clear off the dirt during the intricate five-month project.

Features now clearly visible to passers-by include an ornate frieze of leaves and birds and carved panels of examiners at work and a degree ceremony.

Work was also carried out to repair the lead cupola above the main entrance hall. It is decorated with lead dragons which have copper tongues which ‘waggle’ in the wind.

Built in the 1880s by architect Sir Thomas Jackson, the Grade II listed building is also one of the city’s largest conference and events venues.

Every year its marble entrance foyers and 17 meeting rooms provide a backdrop for events including weddings, business meetings and trade shows.

During the two World Wars the Examination Schools was used as a military hospital. Signs for the “resuscitation room” can still be seen today.

Oxford Civic Society chairman Peter Thompson praised the refurbishment.

He said: “The society is highly supportive – we think this is a fantastic example of the sympathetic and well informed design which is very much what Oxford needs.”

University head of conservation Isobel Hughes paid tribute to the work.

She said: “My job brings me into contact with a lot of Oxford University buildings, and I always enjoy seeing the transformation.

“This project has been particularly special, as we have been able to restore the warm honey-coloured stone and reveal the rich detail of this building, which was a hidden gem on the High Street.”