PARIS (AFP).- Art and architecture fans hoping to experience the glass-enclosed escalators hugging the facade of the Pompidou Centre in Paris will have to wait until next year, as extensive renovation work is carried out on the groundbreaking four-decade-old structure.

The museum said Tuesday that the "caterpillar" escalator as well as the sloping stone plaza in front of the iconic structure were closed to the public Tuesday for work expected to last until September 2020.

As a result, the centre's three million annual visitors will have to use an entrance around back, usually reserved for the vast public library that forms part of the inside-out complex.

While a hit with visitors, the escalator can get unbearably hot under the summer sun, whose rays have taken their toll on the corridors since the Pompidou opened in 1977.

The glass panels in particular, which offer pristine views of the heart of Paris, will be replaced to offer better insulation.

The main entry underneath will also be enlarged and equipped with revolving doors, the museum said.

Designed by star architects Renzo Piano and Richard Rogers, the building's radical design pushes almost all its structural and mechanical elements to the exterior, freeing up vast exhibition spaces.

On full display outside is a maze of blue air-conditioning conduits, green water pipes, yellow electrical casings and red elevators.

The escalator closures come as the Pompidou is preparing for one of this year's major shows in Paris, a retrospective devoted to Francis Bacon.

Because of the expected crowds, tickets will be available only by reservation -- a system recently implemented by the Louvre as well to cope with a huge influx of visitors.

© Agence France-Presse