To look up - and up - at the Real Fábrica de Tabacos is to get a sense of the scale of Seville's tobacco industry in the 18th century. This is one of the largest buildings in Spain (only El Escorial tops it in terms of surface area). It's used as a university building now, but you can still walk around it.
The reason most people visit is to get a vision of Bizet's doomed heroine, Carmen. This building is where she worked and these doors are where she lounged, fresh from rolling cigars on her thighs, to ensnare her lovers.
Carmen's wraith may be compelling, but the wraiths of the real cigar workers - nearly all of them women - also clamor for attention, as do the colonially themed bas-reliefs on the outside of the building.