THRESHOLD Posted on June 10, 2015 by admin Constructed public-private line. Vertical threshold. Front door as back door. Layers from private to public. Commercial threshold. Green semi-public access path. Twin path to single family houses. Is the car a sculpture in the garden? Even the postman is not allowed in. Small space that links between private space and public space. Sometimes called third space as it is between private and public, it allows a smooth transition between interiority and exteriority.