Went with my dad to Australia in 1996 and visited a friend of his who had two 40-foot shipping containers buried side by side in his front yard. He had it stocked with all kinds of food, water, etc. and was fully expecting some sort of apocalypse or world wide disaster event so this was his hideout. The containers were placed side by side and had the connecting walls torched out to make essentially a double wide underground shelter. The entrance was through a coat closet in the house on the property, whereby you pull a specific hook in the closet and a hidden door pops open into the stairwell leading down into the containers. He had similar venting, but disguised them as fountains in his front yard. I wish I had pictures - even just thinking about it makes it seem so far fetched, especially almost 20 years ago.
Beer or wine cellar constructed similarly is awesome. Makes me wish I owned property.