Igreja de Nossa Senhora da Oliveira is a collegiate church in Guimarães, Portugal. It is classified as a National Monument.
The church was founded as a double monastery in about 949 by Countess Mumadona Dias, the widow of Count Hermenegildo González. It was donated to the Catholic Church by King Ramiro II. In 1074/1075, Pope Gregory VII prohibited double monasteries and by 1089 the monastery transitioned to a single monastery. Around 1139, the monastery was turned into the collegiate church . The collegiate church was shut down in 1911, but reopened in 1967.[1]