Located in the popular Calle de Atocha, by the Plaza de Antón Martín, we find one of Madrid's oldest pharmacies, founded in 1870. On the front of the building there is a hot air balloon, after which the pharmacy is named, imitating English chemist shops, which would place this sign on their establishments so that they could be distinguished immediately from herbalists and druggists.

Initially, this pharmacy was situated on the ground floor with a flat above it, and the upper floors were occupied by various tenants, including the Spanish doctor and Nobel Prize winner Santiago Ramón y Cajal. Nowadays, however, this establishment owns the whole building.

During the Spanish Civil War, the building next to the pharmacy was hit by a bomb, and the pharmacy itself was badly damaged.

It is now a large establishment, fitted with the latest technology, where as well as medicines you can find herbalist, homeopathic and over-the-counter products.