Castelinho da rua Apa, Historical building in Santa Cecília, Brazil.

Castelinho da Rua Apa is a three-level stone and stucco house built in 1912, its central tower rising above a flat roofline. A recessed entry with a white panelled door sits at the base, a dark iron balcony railing above it, and two round openings pierce the tower. Tall arched windows flank the centre, and black graffiti marks the left wall.

The Dos Reis family built the house in 1912, modelled on French castles. The father, Virgilio Guimarães dos Reis, died two months before 12 May 1937, when Maria Cândida, 73, and her sons Álvaro, 45, and Armando, 43, were found shot beside a 9 mm Parabellum pistol. The crime was never solved; the property passed to the federal government.

The name "Castelinho" means "little castle", taken from the French-castle model the Dos Reis family used in 1912. Since 1996 the NGO Clube das Mães do Brasil, founded by Maria Eulina dos Reis Hilsenbeck, holds the concession for the house; its adjoining building sells goods made by the people it assists. The 1937 shootings, never solved, made the house a fixture of newspaper, magazine and television reports and gave it a haunted reputation.

The building stands at the corner of Rua Apa and Avenida General Olímpio da Silveira and now functions as a social assistance center. The NGO Clube de Mães operates various support programs here for the local community.

After the deaths, a new federal law no longer recognized nephews as legitimate heirs, which led to the seizure of the property. This legal case contributed to later reforms in Brazilian inheritance law and made the building an unusual example of ownership transfer through legislative change.