Location, design and construction of a landfill of hazardous waste are in focus. The selected site must be physically stable, and an elevated area with good run-off conditions of precipitated water and tight underground is preferable. The detailed design must adaptate to what legislation requires and be decided on the basis of the required operational lifetime. Several concepts have been proposed and two major principles are compared: 1) location above ground on a drained base with a tight top liner and a less tight bottom liner, and 2) placement below ground with clay liners surrounding the entire waste mass. In either case collection of percolated water can be arranged but maintenance over several hundred years cannot be guaranteed. A design that totally eliminates percolation of the waste is ideal but a number of functions of such concepts need to be considered.