My definition of a true 5-star tour guide is one who is responsive to my questions during the pre-signing negotiation process then provides an exceptional tour and later  helps with my post-tour plans. Mercedes did all that so that makes her a true 5-star guide.  She gave us a very enjoyable and informative tour of Madrid, complete with the necessary historical background and she graciously volunteered to take many family photos in various parts of Madrid. To top it all, she even convinced the driver of the minibus (which I booked separately) to give us an extra hour for free so that we don't have to walk back to our hotel after the tour! My entire family of 12 persons was very happy with Mercedes. Thank you, Mercedes!!!