Madrid has many good quality hotels at reasonable prices and a very good public transport system, therefore, we believe it is not necessary to choose accommodation near the conference venue.
ACCOMMODATION
But, if you want to be close to the venue, two nice hotels with reasonable prices are:
Hotel Puerta de Toledo***Glorieta Puerta de Toledo, 4, 28005 Madrid
Hotel Ganibet***
Calle de Toledo, 111 - 113, 28005 Madrid