In 1147, a Portuguese knight named Martim Moniz allegedly wedged his own body into the closing gates of Castelo de São Jorge, holding them open long enough for Christian crusaders to storm through. Whether the tale is true or merely a useful legend, that gate still bears his name.

The fortress itself sits atop Lisbon's highest hill, where Phoenicians, Romans, Visigoths and Moors had each taken turns building fortifications since the 6th century BC. The Moors constructed the castle's bones in the 11th century; the Portuguese spent the next several hundred years adding to it, including installing the royal archives in the Torre de Ulisses, which once held every document of significance to the crown.

Today, the tower houses something rather more whimsical: a camera obscura installed in 1998 that projects live, 360-degree images of Lisbon onto a darkened room. Peacocks strut through the gardens below.

VoiceMap's self-guided audio tour traces the site's Moorish origins and medieval transformations, stopping at the Gate of Martim Moniz to tell the knight's story and at the ruins of the Royal Palace of the Alcáçova to conjure life in the medieval court.