The building houses the Administration of the Municipal Water Supply and Sewerage of the city of Lamia and several other facilities concerning Water Supplies, as well as laboratories and storage areas. The plot is located at the east end of the city of Lamia on the junction of its two main entrance arteries. The designing process aimed to create an iconic Public Building for the city. Therefore, we created an interactive and extroverted building that is open, accessible and welcoming to all of its users. At the same time, a great amount of attention was given to its orientation and placement on the plot, as well as its connection to the city and the designing of the basic structure. The basic characteristic of this project is its sustainable design. By installing a horizontal geothermal system which covers the entire area of the plot, we took advantage of the ground's stable temperature and we reduced the electical consumption needed for heating and cooling to its minimum. Adding to the previous, the placement of solar panels applied on the glass surfaces and on the roof of the building converts it into a zero impact building governed by sustainable and bioclimatic principles. A network of vertical, horizontal and diagonal axes, cuts through the massive volume of the building. This generates multi-shaped surfaces with fissures and gaps and boosts the sense of penetrability of the outer shell of the building. A central atrium was created in the centre of the building's geometric volumes. This inner open space, the plaza, attracts the visitors and generates the building’s main meeting point.