Ask three people in Madrid where to get a NIE and you may hear three addresses. None of them is necessarily wrong: the city divides the work between desks, and the one you need depends on the procedure, not on the district you live in.
Avenida de los Poblados, near Aluche, hosts the SACE that the Delegación del Gobierno lists for NIE assignments, certificates for residents and non-residents, extensions of stay and return authorisations, from 9:00 to 13:30. The same address hosts the Sección de Documentación de Extranjeros, which issues and hands over TIE cards in a morning and an afternoon session.
Avenida Padre Piquer 18 is home to the other SACE. Policia.es lists it for the Certificado de Registro de ciudadanos de la UE, the green certificate that EU, EEA and Swiss nationals hold once resident, and for extensions of stay. If you are an EU citizen registering as a resident, this is usually your address.
Then there is Calle Silva 19, in the centre: the government’s Oficina de Extranjería. It deals with residence and work authorisations rather than police documents, which makes it the address for the files employers prepare for non-EU staff.
Outside the capital, policia.es lists eleven comisarías with a foreigner unit, from Alcalá de Henares and Torrejón de Ardoz to Getafe, Móstoles and Pozuelo de Alarcón, and each of them handles NIE assignments and EU certificates. If you live near one, your booking may send you there instead.
One rule settles every argument: read your cita previa confirmation. It names the office, the address and the time, and it is the only version the desk recognises. If it surprises you, check that you booked the right procedure before setting off. And if the booking system defeats you altogether, the online NIE route offered by Gestoraz is an alternative for the number itself.