By the mid 18th century, the movement broadened to incorporate a greater range of Classical influences, including those from Ancient Greece. The shift to neoclassical architecture is conventionally dated to the 1750s. It first gained influence in England and France; in England, Sir William Hamilton's excavations at Pompeii and other sites, the influence of the Grand Tour and the work of William Chambers and Robert Adam, was pivotal in this regard. In France, the movement was propelled by a generation of French art students trained in Rome, and was influenced by the writings of Johann Joachim Winckelmann. The style was also adopted by progressive circles in other countries such as Sweden and Russia.