Complex sentence: Bethlem was not initially intended as a hospital, much less as a specialist institution for the insane, but as a centre for the collection of alms to support the Crusader Church and to link England to the Holy Land.
Split into simpler sentences: Bethlem was not initially intended as a hospital much less as a specialist institution for the insane. Rather, the ostensible purpose of the priory was to function as a centre for the collection of alms to support the Crusader Church and to link England to the Holy Land.