Open all year during reasonable daylight hours; no admission charge. Cadw asks visitors to keep pets on leads and not to approach the livestock that may graze the field, especially in spring and summer, and may close monuments at short notice in extreme weather.
Terrain level 3, moderate: steps and a kissing gate at the field entrance, then uneven grass that is muddy and slippery when wet; do not climb on the stones. No toilets or facilities; the nearest are at Dyffryn Gardens. Drones are not permitted.
Dogs: Dogs are welcome on leads at the tomb; keep them on a short lead and away from any livestock in the field. The open field around the tomb is the whole visit and is open to dogs on a lead; livestock may graze. The site is free. Vale Trail 7 across the surrounding fields asks for dogs on a lead because of livestock.
Photo: The lichen-covered capstone of St Lythans burial chamber on its three tall uprights, open to the east, in a grass field with trees beyond. M J Roscoe, CC BY-SA 2.0. Source: https://commons.wikimedia.org/wiki/File:Gwal_y_Filiast,_St_Lythans_-_geograph.org.uk_-_5896721.jpg. Licence: https://creativecommons.org/licenses/by-sa/2.0. Resized and cropped for display; derivatives retain the source licence.