Dental drill? No, a 4 storey high drill. I was at a tour of the construction site behind the "Triangeln" shopping center/Hotel Sheraton in Malmoe, Sweden, today. The construction is for an extension of the 3 storey shopping center and the underground parking garage, plus an 11 storey apartment building. The geo-engineer explained that two parallel concrete guide walls were first poured into cuts in the ground. Using the walls as exact guides, this drill would make 4 storey deep holes in the ground. Then another machine would chew up the material between the holes. Thereafter, cages of reinforcing iron rods would be lowered into the rectangular holes, after which concrete would be poured into the hole. Once the concrete had set, a floor would be poured. Next the area under the floor would be excavated and another floor poured. And so on, down to 4 storeys under ground level. This is called building from the top down. I'll post a photo of the other cutting machine for making rectangular holes tomorrow. Enjoy!