Allow plenty of time here. Make use of the audio guide - and then read the other well displayed information, and exhibits. Also allow at least 30 minutes to roam the tunnels that were used during the war. There is audio information for them too. You can spend longer just roaming these tunnels imagining living here. Make sure you find the 'surgery' which had its own entrance, as well as the birthing room. So allow at least 2 and half hours to make the most of the information and exhibits available. This is one of the four venues on the Combined ticket, which is really good value.