Abstract: A building-wall-layout tool has a pair (29) of two line holders (1, 30, 31), each of which have spike legs (10, 12, 25) for being driven into ground material (13) proximate opposite ends (36, 42) of an intended wall (35) of an intended concrete slab for an intended building. Each of the line holders include a fastener section (2) and a handle section (3). The fastener section includes a fastener slot (6) extended from proximate a first side to proximate a second side of the fastener section. The fastener slot is articulated for receiving at least two line fasteners (7, 8) which are articulated for being slid in the fastener slot and affixed removably to sides of the fastener slot selectively intermediate the first side and the second side of the fastener section. The line fasteners are articulated for receiving and retaining indicator lines (40, 41) designedly.