A dual-unit paving system for covering a surface. The system comprises pairs of first and second units. For each pair, the first and second unit have different respective shapes and sizes, and are configured to be matingly engageable for forming a hexagonal assembly having six, non-linear sides. The hexagonal assembly allows forming rotational tessellations. The first and second units are also shaped and configured to be matingly engageable so as to form horizontally aligned tessellations, and also vertically aligned tessellations.