This book investigates the accounts of six European non-Muslims who managed to secretly visit the cities of Makkah and Madinah and to record their travels as well as impressions. The protagonists were Ludovico di Varthema from Italy, Vincent le Blanc from France, Joseph Pitts from England, Ali Bey el Abbassi (Domenec Francesc Jordi Badia i Leblich) from Spain, John Lewis Burckhardt from Switzerland, and Richard Francis Burton from England. The six men performed their feats in their capacities as adventurers, explorers, soldiers, and spies. One yet was a slave. The visits spanned a period of three and a half centuries, from 1503 as the time of the first visit by Ludovico di Varthema, to 1853 as the time of the visit by Richard Francis Burton. The period covered was perhaps one of the most dramatic periods in the history of the Hijaz region in particular, and also in the history of Islam-West (Orient-Occident) relations, in general. The visits and the travellers' accounts reveal much about challenges faced by Islamic culture and civilization in early modern times. Those challenges pertained to the rise of Western civilization and its imperialistic tendencies, modernization, radical anti-Islamic polemics, the waning of Islamic civilization, and Muslim schism. Travels had to be secret, meticulously planned, and perfectly executed. One ostensibly had to embrace the religion of Islam and to live like a Muslim. The pilgrimage (hajj) season was the most conducive circumstance for the purpose on account of the vast and varied multitudes that visited Makkah and Madinah, "exposing the traveller only to stand the buffet with knaves who smell of sweat". Hence, not too many people embarked on the mission. The places were holy and exclusive, so, attempting to succeed entailed myriads of monumental challenges and life-threatening dangers. The matter, by no means, was for the faint-hearted.