<prompt> Translate the following text to EnglishMadriidi ya kale ni ya zamani sana, lakini kuna sehemu za kale zaidi za jiji katika kuta za Kiarabu na pia kuna maeneo mengine mengi ya kuvutia ambayo yanaweza kufanywa katika eneo hili ambalo linaanzia Mto Manzanares na Palacio Real Jumba la Mfalme, kwa kweli urithi wa watawala wa baadaye wa Bourbon hadi Puerta del Sol, bado kituo cha neva cha Madrid.  <response>: Little remains of medieval Madrid, but there are glimpses of the oldest parts of the city in the Arab walls and several attractive small plazas, as well as many other discoveries to be made in this area that extends from the River Manzanares and Palacio Real Royal Palace, actually the legacy of the later Bourbon rulers to the lively, congested Puerta del Sol, still the nerve center of Madrid. 