Waldensians, Waldenses or Vaudois are names for a Christian movement of the later Middle Ages, descendants of which still exist in various regions, primarily in North-Western Italy. There is considerable uncertainty about the earlier history of the Waldenses because of a lack of extant source material. They were persecuted as heretical in the 12th century onwards, and endured near-annihilation in the 17th century. [...] Seen by the Roman Catholic Church as unorthodox, they were formally declared heretics by Pope Lucius III in 1184 at the Synod of Verona, and by Pope Innocent III during the Fourth Lateran Council in 1215.[5] In 1211, more than 80 Waldensians were burned as heretics at Strasbourg, beginning several centuries of persecution that nearly destroyed the movement. Part of their legacy is recognized as works of the writer Henri Arnaud. The Waldensian Church of Italy has survived to the present day. [...] According to modern scholars and the Waldensians themselves, the Waldensians began with Peter Waldo, who began to preach on the streets of Lyon in 1177. Peter Waldo preached without permission of the Roman Catholic Church and by the early 1180s he and his followers were excommunicated and forced from Lyon. The Roman Catholic Church declared them heretics — stating the group's principal error was "contempt for ecclesiastical power". The Waldensians were also accused by the Catholic Church of teaching "innumerable errors". [...] In 1848, after many centuries of harsh persecution, the Waldensians acquired legal freedom in the Kingdom of Piedmont-Sardinia as a result of the liberalising reforms which followed Charles Albert of Sardinia's granting a constitution (the Statuto Albertino). Subsequently the Waldensian Evangelical Church, as it became known, developed and spread through the Italian peninsula. The Waldensian church was able to gain converts by building schools in some of the poorer regions of Italy, including Sicily. There is still a Waldensian church in the town of Grotte, Province of Agrigento at the southwest part of the island.