continent. Italian architect Luigi Vanvitelli son of Dutch architect Caspar van Wittel built the Royal Palace in Caserta in c. 1750. He contributed to the construction of many neoclassic-style palaces in which the nobles of Naples spent their holidays. These palaces are now known worldwide as "Ville Vesuviane". Raimondo di Sangro, prince of Sansevero, was a scientist and one of the last alchemists. Around this time, in 1786, German writer Goethe visited Campania and Naples. German archaeologist Johann Joachim Winckelmann also visited Naples, Paestum, Herculaneum and Pompeii in 1748 and later, studying how archaeological surveys were conducted in the kingdom of Naples. He was one of the first to study drawings, statues, stones, and ancient burned scrolls made of papyrus found in the excavations of the city of Herculaneum. Archaeological excavations in Pompeii were initiated by King Charles III of Naples in 1748. He issued the first modern laws in Europe to protect, defend and preserve archaeological sites. Neapolitan musicians of that period include Niccolò Antonio Zingarelli and Giovanni Paisiello. Musician Gioachino Rossini lived for several years in Naples, where he wrote numerous compositions. Italian poet and writer Giacomo Leopardi established his home in Naples and Torre del Greco, remaining there at the end of his brief young life. He died at Naples in 1837. The first volcano observatory, the Vesuvius Observatory, was founded in Naples in 1841. Geologist Giuseppe Mercalli, born in Milan in 1850, was a director of the Vesuvius Observatory. In February 1851, British statesman William Ewart Gladstone was allowed to visit the prison where Giacomo Lacaita, legal adviser to the British embassy, was imprisoned by the Neapolitan government, along with other political dissidents. He deplored their condition, and in April and July, he published two Letters to the Earl of Aberdeen against the Neapolitan government, followed by An Examination of the Official Reply of the Neapolitan Government in 1852. His pamphlets may have contributed to the cause of the unification of Italy in 1861. French writer Alexandre Dumas, père was directly involved in the process of the Unification of Italy and sojourned two or three years in Naples, where he wrote several historical novels regarding that city. He was also a known newspaper correspondent. Francesco de Sanctis, writer, politician and twice Minister of Instruction after the reunification of Italy in 1861, was born in Morra De Sanctis near Avellino. German scientist Anton Dohrn founded in Naples