San Silvestre Hortaleza is a local running race in Madrid's Hortaleza district, held in December as part of Spain’s end-of-year San Silvestre race tradition. The event begins in the late morning and includes adult and children’s entries, with the race structured around a neighborhood format rather than an elite-only field.
The source does not give route details, but it does give the event’s clearest extra purpose: each adult entry sends 2 euros to Ayúdame 3D, and each child entry sends 1 euro. Ayúdame 3D is a Spanish social organization that designs, prints, and ships prosthetic arms free of charge to amputees and disabled people around the world, including a mechanical arm made for people without an elbow.