Taking its title from the names of two clock manufacturers, “RHYTHM, CITIZEN” unfolds as a series of cryptic, meditative encounters with time. Weaving through the vaulted rooms and colonnaded corridors of the monastery-like architecture of Grazer Kunstverein, the exhibition is billed as Maria Toumazou’s “first institutional solo presentation,” but it brings together a large cast of collaborators, including Felix Taylor (Platten Haus), Koula Savvidou, and Marietta Mavrokordatou. Through various apparatuses, each artist responds to an implied prompt: How is time halted, set into motion, or embodied