When did Edward Gibbon finish writing The History of the Decline and Fall of the Roman Empire?

Edward Gibbon finished writing his monumental work, The History of the Decline and Fall of the Roman Empire, on June 27, 1787.1

While the six-volume series was published over a period spanning from 1776 to 1788, Gibbon completed the final lines of the manuscript while living in Lausanne, Switzerland. The concluding three volumes were subsequently published in London on May 8, 1788, which coincided with the author's 51st birthday.213