Any construction engineers here? How would one go about building something like this? Do you have to dig a hole big enough to build the whole thing in, then re-fill the sides with sand? Is it possible to gradually go deeper, i.e. build a level <i>under</i> an existing level, or do you have to wait for the dry season and then rush to get it completed before the lowest levels are flooded come the next wet season? That seems impossible, given the size of some of these things.<p>I&#x27;m wondering because I&#x27;d like to build a wine cellar similar in concept to these things (a spiraling staircase with an entrance from above only), but I want to get some insight into building methods before inviting contractors. (for anyone who like underground structures, see www.spiralcellars.co.uk ).