The Ty Mawr standing stone is located just a short distance north-west of the Trefignath Burial Chamber (also open access and also in the care of Cadw). For that reason, you may sometimes see it referred to as the Trefignath Standing Stone.
Unfortunately, the encroachment of modern civilisation means that the stone is surrounded by modern buildings and quite near the busy A55 trunk road. On the other hand, there are good views north to Holyhead Mountain!
Getting There
Ty Mawr is not well signposted. The stone stands alone in a farm field on Parc Cybi, immediately opposite the Holyhead Inland Border Facility complex and just past the Premier Inn drive.
The simplest way to reach the site is to take the A55 and exit at Junction 2. Turn left onto the A5153 and then left again onto Parc Cybi. Pass the Premier Inn drive and you will see the stone in the field to your left, opposite the Border Facility.
There is no dedicated parking, but we found it easy to pull off the road. Take the obvious path along the field boundary and you will see a small sign marking your way into the field. The stone will be directly ahead of you.