Floroz, now that you mention it, I remember now taking photos of the beautiful, semi-spiralling wooden staircase at Hostal Oporto so I guess there was no elevator. ... and they're at Calle de Zorrilla, 9 - º1 right next to Hostal Mirentxu. (see below)

As for Hostal Mirentxu , according to their address, Calle de Zorrilla, 7 - º3, they're on the Spanish 3rd floor or (Wow) the 4th floor equivalent in the USA. "Planta Baja" is always the ground floor and the 1st Floor is the next floor UP. Comparing Hostal Oporto at º1 (which we know and agree that it's one floor UP from the ground floor) that must mean that Hostal Mirentxu is on the 4th level or 3rd level ABOVE the ground level. Well, send Mirentxu an email about the elevator but I don't think they have one (but I've been wrong before).

Saludos, MadridMan