Excellent stay right in the center of the old town in a large, clean, light, safe, pretty quiet flat in this very old, historic building. The bedroom is comfortable and simple but not too small and with high ceiling and a window over the street. I never met Marta but she was quick and responsive by text. Junior who lives there (her adult son? not sure) has a suite on the other side of the entry and he is kind, courteous, and helpful.
The street and neighborhood felt very safe and I had no problems. Bullring, river, and cathedral are all just a few blocks away.
Caveat for those sensitive to heat: the apartment has no a/c and the temperature in Sevilla is consistently above 100F from May through summer. It was 106F to 111F every day the week I was there. Even with the provided fan, it is very hot at night for sleeping. I don’t mind heat too much generally so it was OK for me (though I sweated all night), but for those sensitive to it, I would recommend you stay elsewhere. Otherwise, great stay!