The monumental complex of the Fortezza da Basso was built in 1534, with the return to power in Florence of the Medici family after the dramatic siege of 1529-30, on the outskirts of a mediaeval city from a design by the great architect Antonio da Sangallo the Younger. This sophisticated military machine, a splendid example of the celebrated fortresses built by the Sangallo family, was constructed in record time during the reign of Duke Alessandro under the growing threat of
turbulent political upheavals. It was one of the very first Italian "citadels" and seems rather to have been built as a protection against the city's inhabitants than from its external enemies. Paradoxically enough, throughout all its long history, which dates from 1533 when Sangallo received his commission, this impregnable fortress was never once attacked and has thus remained intact to this day.
Nowadays the fortress is used for all of the most important Florentine exhibitions and fairs. The Central Pavilion that stands in the center of the great square inside the fortress was designed by architect Pierluigi Spadolini and was inaugurated in 1977. It is built on three floors: the Ground level will host the GeoExpo2004, a large exposition area, and a smaller area with the registration desks, slides center, Scientific Program Office, Meeting rooms and other facilities.
On the other levels there are rooms in which the scientific session will run from 9.00 to 17.00.

Ancient buildings surround the Central Pavilion:
- The Teatrino Lorenese in which the Science Theatre and the First Intern. Earth Science Film-Festival will be held.
- The Cavaniglia Pavilion in which you will enjoy listening to the plenary lectures given by eminent scientists.
Here the General Assembly and the IGC Councils will also take place.
- The Arsenal in which the Poster Session will take place every day from 17.00 to 18.30.
- In the Arsenal and in the Rastriglia Pavilions you will spend the lunchtime enjoying the Italian cuisine.