Police are urging drivers to plan ahead and expect possible delays in the Gwalchmai area ahead of the 2026 Urdd National Eisteddfod.
Final preparations are continuing at the Mona showground, where Europe's biggest youth festival gets underway on Saturday - the first time it's been held on Anglesey since 2004.
North Wales Police say there will be increased traffic in and around the showground over the coming days as the festival is set up and visitors start to arrive.
A NWP spokesperson added: "We encourage all visitors, whether local or travelling from further afield, to plan their journeys in advance and follow clearly marked road signage, using public transport where possible."
"Drivers are urged to take extra care near the Maes, remain alert to pedestrians, and follow temporary traffic arrangements that will be in place to ensure the safety of all road users and the local community."
Urdd organisers are encouraging drivers to follow official yellow signs to get to the Maes, after leaving the A55 at junction 6 - the Nant Turnpike interchange.
In terms of public transport, the nearest train stations are Llanfairpwll (9 miles away) and Ty Croes (five miles away - request stop) with the Maes on the 4A bus route between Bangor and Holyhead.
Spaces for secure bicycle parking are available at the Welcome Centre but organisers say they do not recommend walking to the Maes as there is no pavement leading to the showground.


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