But a more probable source of inspiration in the art of building are the Romans, who established the famous collegia of architects referred to in the list of alternative theories given in the _Masonic Cyclopædia_. Advocates of the Roman Collegia origin of Freemasonry might be right as far as operative masonry is concerned, for it is to the period following on the Roman occupation of Britain that our masonic guilds can with the greatest degree of certainty be traced. Owing to the importance the art of building now acquired it is said that many distinguished men, such as St. Alban, King Alfred, King Edwin, and King Athelstan, were numbered amongst its patrons,[269] so that in time the guilds came to occupy the position of privileged bodies and were known as "free corporations"; further that York was the first masonic centre in England, largely under the control of the Culdees, who at the same period exercised much influence over the Masonic Collegia in Scotland, at Kilwinning, Melrose, and Aberdeen.[270] But it must be remembered that all this is speculation. No documentary evidence has ever been produced to prove the existence of masonic guilds before the famous York charter of A.D. 936, and even the date of this document is doubtful. Only with the period of Gothic architecture do we reach firm ground. That guilds of working masons known in France as "Compagnonnages" and in Germany as "Steinmetzen" did then form close corporations and possibly possess secrets connected with their profession is more than probable. That, in consequence of their skill in building the magnificent cathedrals of this period, they now came to occupy a privileged position seems fairly certain. The Abbé Grandidier, writing from Strasbourg in 1778, traces the whole system of Freemasonry from these German guilds: "This much-vaunted Society of Freemasons is nothing but a servile imitation of an ancient and useful _confrèrie_ of real masons whose headquarters was formerly at Strasbourg and of which the constitution was confirmed by the Emperor Maximilian in 1498."[271]