The Nixie Concrete Clock by Daniel Kurth, is one-hell-of a timepiece Iâve ever come across. Depicting time are six nixie tubes, reinforced in a concrete block. Itâs a working prototype, inspired by the vintage Z560M Nixie tubes. Sleepless nights are inevitable if it hung right over your head, on the wall. For your information, the current time being displayed is 10:28:09.