A hypergraph is called an r × r grid if it is isomorphic to a pattern of r horizontal and r vertical lines, i.e., a family of sets {A 1 , . . . , A r , B 1 , . . . , B r } such thatA hypergraph is linear, if |E ∩ F | ≤ 1 holds for every pair of edges.In this paper we construct large linear r-hypergraphs which contain no grids. Moreover, a similar construction gives large linear r-hypergraphs which contain neither grids nor triangles.For r ≥ 4 our constructions are almost optimal. These investigations are also motivated by coding theory: we get new bounds for optimal superimposed codes and designs. *