Have a look at this engraving. Its story begins with the discovery of the grandeur of Borobudur by, interestingly enough, an Englishman, as early as in 1815 (when Java was under British colonial rule): Sir Thomas Stamford Raffles. In London in 1817, Raffles published the first engravings showing the site and the first bas-reliefs which were extremely comical (and which, unfortunately, have never been reproduced elsewhere). The engraver, a Brit on of London, had never visited the monument; dissatisfied with Raffles' draftsmanship, he transformed his work into Greek Neoclassic versions, which brings us to our present image: it could be mistaken for the altar of Perga mum!
No major restoration was undertaken until the end of the 19th century: the first was instigated by a specialist from Leyden (since Java was by then under Dutch colonial rule), Dr. C. Leemans. Due to limited financial resources, Leemans saw to the most urgent needs, and if the monument was able to be rescued a century later, it is in large part thanks to Leeman's initiative. The first truly large-scale restoration was carried out between 1907 and 1911 by a Dutch second lieutenant and engineer, Theodoor van Erp. However, none of these specialists encountered the problem of pollution and stone rot plaguing the monument more recently. A comparison between a photo taken of Borobudur in 1910 and one in 1960 shows the extent to which the stones were spotted and eroded and how far its earthen core had sunk.
A first restoration with the support of UNESCO was accomplished in 1948. In the sixties, an appeal from Indo nesia was answered by international support on behalf of restoration efforts carried out jointly by the Indonesian government and UNESCO. The results of this project, lasting from 1971 to 1984, are what you now see.
Another minor restoration was necessary after a bomb attack to the summit of Borobudur damaged several of the stone-latticework-surrounded stupas, alas proving that this magnificent shrine is no safer from harm than any of the other jewels constituting the cultural heritage of mankind.