I find from the link below that the Basilica of Our Lady of Guadalupe in Mexico City is given the Spanish epithets 'insigne y nacional', and that these epithets are so fixed that there is a device for the church consisting of the letters I.N.B.G Therefore the whole phrase would mean in 'In the glorious national Basilica of Our Lady of Guadalupe'. I think there is no problem about 'ecclesia' and 'Basilica' being taken together to mean 'Basilica', since a basilica is a church of a particular status. 'Basilical church', if you want word for word.