When we enter the Metrology Museum, we find ourselves in a rectangular space, with a gap, equally rectangular, in the center, from which emerges the Balance of the Casa da Índia (House of India). The Balance hangs from the ceiling of the Museum, and the plates rest on the lower floor. 

Around the Balance, seven showcases are currently visible on one side, showing us various pieces and instruments, grouped in a logic that is based on the measure (volumes of solids, liquids, length or mass) or related to activities related to metrology, such as the measuring profession. 

On the opposite side, some display cases show some pieces, typically more recent, related to other measures(electricity, luminous intensity), some typical instruments of the 20th century associated with metrological control (meters, taximeters) or other pieces of historical interest (meter comparator in invar). 

In this space, next to the windows, we also find some interesting instruments, such as the Balance of the Fábrica de Pólvora de Barcarena (Barcarena Gunpowder Factory), the standard gas meter of the mid-20th century or a specimen of balance with a particularly interesting decoration. We know several identical specimens of this balance have been used in some parts of the country, in different contexts, such as butchers and fairs. 

This space allows access to the Permanent Exhibition, in an adjoining room, through two passages, one as an entrance and the other as an exit the Permanent Exhibition, which is organized in order to show the evolution of metrology in Portugal. 

The pieces presented in these two spaces were part of a unique exhibition that was open until 2016, in another space, normally closed, which was only accessible for visits after prior request. 

On July 12, 2016, the date of the 30th anniversary of the IPQ, it was possible to inaugurate these new and much wider installations of the Museum, with two large rooms, which allowed to separate in different spaces the pieces that should be included in the Permanent Exhibition, from the others we see in this entrance room, which can be used for temporary exhibitions.