Ávila is not what I'd consider a "cheerful" place...it's of course picturesque, historical, and monumental, but the imposing city walls, Gothic churches, and somber stone architecture gives it a solemn and somber atmosphere. That's why entering into the bright Santa Teresa Convent is such a welcome shock to the system.
The convent is free to visit, and when you enter you find a gleaming white hall filled with warm sunlight filtering through the windows and cheerful choir music emanating from some unseen speakers. It makes you want to sit down and take it all in for a few minutes. It's a surprising ray of cheerfulness and light in an otherwise grey and somber Ávila.