A dual-unit paving system for covering a surface, the system comprising: pairs of first and second units (A, B) wherein for each pair: the first unit has a lower face for facing the ground, an exposed upper face, and sidewalls extending from the lower face, the sidewalls of the first unit including a top side, a bottom side, a left side and a right side (12, 14, 16, 18), the second unit has a lower face for facing the ground, an exposed upper face and sidewalls extending from the lower face, the sidewalls of the second unit including a top side, a bottom side, a left side and a right side, the second unit having a shape different from a shape of the first unit; the bottom side of the first unit has a non-linear, irregular outline matingly engageable with an outline of the top side of the second unit for forming a hexagonal assembly having six, non-linear sides, said hexagonal assembly allowing to form rotational tessellations; the left side and the right side of the second unit have non-linear, irregular outlines matingly engageable to at least respective portions of outlines of the right side and left side of the first unit, allowing to form horizontally aligned tessellations, and the outline of the bottom side of the first unit comprises the outline of the top side of the first unit, and the outline of the top side of the second unit comprises the outline of the bottom side of the second unit, allowing to form vertically aligned tessellations. pairs of first and second units (A, B) wherein for each pair: the first unit has a lower face for facing the ground, an exposed upper face, and sidewalls extending from the lower face, the sidewalls of the first unit including a top side, a bottom side, a left side and a right side (12, 14, 16, 18), the second unit has a lower face for facing the ground, an exposed upper face and sidewalls extending from the lower face, the sidewalls of the second unit including a top side, a bottom side, a left side and a right side, the second unit having a shape different from a shape of the first unit; the bottom side of the first unit has a non-linear, irregular outline matingly engageable with an outline of the top side of the second unit for forming a hexagonal assembly having six, non-linear sides, said hexagonal assembly allowing to form rotational tessellations; the left side and the right side of the second unit have non-linear, irregular outlines matingly engageable to at least respective portions of outlines of the right side and left side of the first unit, allowing to form horizontally aligned tessellations, and the outline of the bottom side of the first unit comprises the outline of the top side of the first unit, and the outline of the top side of the second unit comprises the outline of the bottom side of the second unit, allowing to form vertically aligned tessellations. the first unit has a lower face for facing the ground, an exposed upper face, and sidewalls extending from the lower face, the sidewalls of the first unit including a top side, a bottom side, a left side and a right side (12, 14, 16, 18), the second unit has a lower face for facing the ground, an exposed upper face and sidewalls extending from the lower face, the sidewalls of the second unit including a top side, a bottom side, a left side and a right side, the second unit having a shape different from a shape of the first unit; the bottom side of the first unit has a non-linear, irregular outline matingly engageable with an outline of the top side of the second unit for forming a hexagonal assembly having six, non-linear sides, said hexagonal assembly allowing to form rotational tessellations; the left side and the right side of the second unit have non-linear, irregular outlines matingly engageable to at least respective portions of outlines of the right side and left side of the first unit, allowing to form horizontally aligned tessellations, and the outline of the bottom side of the first unit comprises the outline of the top side of the first unit, and the outline of the top side of the second unit comprises the outline of the bottom side of the second unit, allowing to form vertically aligned tessellations.