Commemorative plaque to Fernando de Castro, Madrid

The commemorative plaque to Fernando de Castro stands on a residential building at Calle de Juan de Austria 22, in Madrid's Chamberí district, a short walk from Paseo de Eduardo Dato.

Who was Fernando de Castro?

Fernando de Castro (1896–1967) was a Spanish neuroscientist, regarded as one of the last direct disciples of Santiago Ramón y Cajal, the father of modern neurohistology. Working within the Cajal school of neuroscience, Castro is best known for identifying the carotid body (glomus caroticum) as the first blood chemoreceptor ever described — a small structure that detects changes in oxygen and carbon dioxide levels in the bloodstream and helps regulate breathing. The discovery remains a reference point in physiology and neuroscience research today.

What does the plaque say?

The inscription states that Fernando de Castro lived, worked, and died in this house. It was unveiled in 1997 on the initiative of the Madrid City Council (Ayuntamiento de Madrid), part of a broader municipal program marking buildings linked to figures who shaped the city's scientific and cultural life — similar plaques appear throughout Chamberí and neighboring districts.

How do you get there?

The address, Calle de Juan de Austria 22, sits in a quiet residential stretch of Chamberí, between Paseo de Eduardo Dato and Calle de Fernández de la Hoz. The closest metro stations are Iglesia (Line 1) and Rubén Darío (Line 5), both a few minutes' walk from the plaque. Several EMT bus lines running along Paseo de Eduardo Dato and Calle de Santa Engracia also serve the area.

What else is nearby?

Chamberí is one of Madrid's most distinctive 19th-century bourgeois neighborhoods, lined with elegant apartment buildings from the turn of the last century. Nearby highlights include the former Chamberí metro station, now preserved as the Andén 0 museum, the Glorieta de Rubén Darío square, and the handsome façades along Paseo de Eduardo Dato. Walking this part of the city offers a glimpse of old Madrid away from the crowds of the historic center.

When is the best time to visit?

Since the plaque sits on the building's exterior, it can be viewed at any time of day or year. Spring (April to June) and early autumn (September to October) are the most pleasant seasons for exploring Chamberí on foot, with mild weather and quieter streets than in summer.

Frequently asked questions

What did Fernando de Castro discover? He identified the carotid body, a small structure at the fork of the carotid artery that acts as the body's first known blood chemoreceptor, sensing oxygen and carbon dioxide levels to help regulate breathing.

When was the plaque installed? In 1997, on the initiative of the Madrid City Council.

Can visitors go inside the building? No — the plaque is mounted on the exterior façade and can be viewed from the street at any time.

What's the fastest way to reach the plaque from central Madrid? Take the metro to Iglesia (Line 1) or Rubén Darío (Line 5), then walk a few minutes to Calle de Juan de Austria.