People keen to see the Bayeux tapestry faced online queues of up to nine hours when tickets went on sale for the first time on Wednesday morning.
The British Museum, which is hosting the tapestry from September, saw huge traffic to its ticketing website as a scramble for access began.
There were reports of 40,000 people queueing by mid-morning, with that figure ballooning to almost 80,000 by mid-afternoon.
Those queueing online were told: "We're currently experiencing high levels of demand. Booking online is still recommended however wait times may extend up to nine hours."
Those waiting were asked to "be patient" and were advised queueing online was still a better option than contacting the museum's "exceptionally busy" phone lines or email inbox.
Ticket sales were for slots between September and December.
Two other releases will follow in October and January for the remainder of the tapestry's historic stay in Britain, which runs until July 2027.
Tickets are priced at £33 during peak times, which is more than triple the €12 (£10) charged where it is normally on display in Normandy.
Off-peak tickets will cost adults £27; it is estimated that the British Museum could generate more than £8.6m from the exhibition.
The museum's director, Dr Nicholas Cullinan, defended the ticket prices in advance of the sale.