Location: White Hill, Berkhamsted, Hertfordshire, HP4 1LJ
Cost: Free (donations welcome)
Parking: There is limited free parking outside, otherwise you can pay to park at the railway station which is very close by
Information: Berkhamsted Castle is owned by English Heritage but is free to visit, it was build in around 1070 and is just ruins now but its quite fun to visit. There is plenty of green space within the ruins and other people visiting had picnics, footballs and bikes, so you could take other bits to do as well while you are there.
There are little plaques around the ruins and a visitor centre so you can learn about the castle on your visit and there is a motte to climb, with a well on the top and little places to explore while you are there. It is pushchair friendly but if you wanted to explore everything you would really need to take babies in a carrier.
We were there for about an hour and a half but if you were relaxed and you took other bits to do, you could spread your visit out longer. Be aware that there are no facilities onsite but you can use the toilet at the station nearby,
It is open 10-6 in summer and 10-4 in winter and is open 7 days a week. Dogs are allowed to visit (but must stay on a lead).
For more information visit their site.