In the late 17th century the Inn suffered a series of disastrous fires, which taken together substantially depressed its fortunes, already weakened by the Civil War and the changes in the legal system, and impoverished it for years.
The most damaging was that of 1684, which destroyed among other buildings the library and its contents. It had been preceded by another fire in 1680 which destroyed much of Gray's Inn Square and was followed by the third in 1687, which damaged Holborn Court (now South Square).
At around the same time it was discovered that many of the buildings not burnt down were in such disrepair that they were near a state of collapse or ruin.
The decline of the Inn to which the fires largely contributed lasted until almost the end of the 19th century.