When the Count-Duke of Olivares ordered to built the palace and gardens of the Buen Retiro to Philip IV in XVII century, he did not imagine that in later centuries, after reforms of other kings of different dynasties or damage of future wars, the garden would be one of the most important green lungs of the world, where there is not only flora, but also their small palaces, ponds, fountains, sculptures and, of course, its history.
The meeting point you have it marked on the map and then visit:
Argentina's Walk. Sculptures of Spanish monarchs.
Monument to the Fallen Angel.
Monument to Alfonso XII and pond
Gate of Alcalá
Walking about 2 hours depending on the group.