Reforma 108 is a residential project located in San Ángel, in the southern part of Mexico City. The plot of land has a rectangular shape with dimensions of 10 x 20 meters. The concept of the house establishes a dialogue between negative and positive space. We aimed to create a play of counterparts, where the negative space and the positive space would define each other and virtually contain empty space. We divided the land into two equal parts. In one part, a longitudinal block measuring 5 x 20 meters was constructed, which corresponds to the house. The other part of the land was conceived as a negative space, contained within the same structure. The negative space functions as a public area or simply an unoccupied open space. The construction of the house thus engages in a dialogue with its counterpart through a facade that gives the illusion of completely opening one side. The only enclosed spaces preserved in the house are the kitchen and bathrooms. The counterpart to the facade is a solid wall with the height of the constructed area and the facade, which limits visibility with the neighbours and provides privacy to the house.