Cut the blocks to build the igloo out from hard packed snow and use the largest of the blocks as a base for the structure. smooth out the edges of the blocks and start placing them in a circle going upwards. Best to use sticks to support the building of the structure in order to avoid it from collapsing. After the structure is completed, use soft snow to fill the gaps and openings the dome may have, then make it smooth on the inside and outside. Air holes should also be made in the wall of this structure for better air ventilation. People who live in these igloos survive in these because they help keep the heat inside for insulation.They have been used by the eskimos and other groups of people for centuries to live and endure through harsh cold environments. A fire could even be made inside of an igloo to help keep warm. These little snow homes are great when living in cold and snow covered places because they are better in protecting you from the elements than most other primitive shelters.