From the airport:

• Take Metro Line 8 to the Nuevos Ministerios stop
• Then take Metro Line 6 to the Diego de León stop

From the Nuevos Ministerios stop reached by

• C1, C3, C4, C8 or C10
• Take Metro Line 6 to the Diego de León stop

From the Atocha train station reached by all train and shuttle lines:

• Take Line 1 to the Sol stop
• Change to Line 2 to the Manuel Becerra stop
• Then change to Line 6 to the Diego de León stop