Open all year and viewed externally during reasonable daylight hours; the tower interior is not open. No admission charge and no castle ticket needed. Cadw may close monuments at short notice in extreme weather.
Terrain level 1, accessible: level mown grass beside a tarmac lane. Toilets at the castle visitor centre during castle hours. Drones are not permitted.
Dogs: Cadw: 'Dogs welcome'; an open-air exterior-only site at ground level on a public green, with no lead sentence on the page. Cadw's Denbigh Town Walls page says dogs are welcome on the walls, which are walked by key from the castle.
Photo: The battlemented tower of St Hilary's Chapel on the green below Denbigh Castle, with autumn woods and the Vale of Clwyd behind. Jeff Buck, CC BY-SA 2.0. Source: https://commons.wikimedia.org/wiki/File:Tower_of_St_Hilary%27s_Chapel,_Denbigh_-_geograph.org.uk_-_4702616.jpg. Licence: https://creativecommons.org/licenses/by-sa/2.0. Resized and cropped for display; derivatives retain the source licence.