The city's most beautiful hidden azulejos, the head of a serial killer from Lisbon preserved in formaldehyde, the Kabbalistic on the south portal of the Hieronymites monastery, or the theory of the Fifth Portuguese Empire, the exceptional panoptic architecture of a former hospital, a tropical botanical garden that contains the remains of the Portuguese World exhibition, the impressive wax masks of the Museum of Dermatology, a secret passage at the Avenida Palace Hotel, the mysterious underground abbey of Palácio Foz, the reason why the Portugal's coat of arms is inclined at 17 degrees on the façade of Rossio station..