Get to know the interior of the old Madrid Post Office building and contemplate the views of Madrid's oldest street, the Gran Vía, from its rooftop,See the Retiro pond that was built by order of Philip IV to recreate naval battles in it,Admire the beauty of the Crystal Palace and discover why it resembles a greenhouse,Discover the symbolism hidden in the statue of the Fallen Angel and the reason why it is situated at 666 metres above sea level