Sintra must have some kind of record for most castles within city limits. Elizabeth and I ventured through two castles during our day-trip to Sintra (and saw another from afar) but there were at least three other castles we could have visited!
The Moors Castle is believed to date back to the 9th century and was used as a military fortress.
Parque Pena Castle: A 19th Century Portuguese Romantic Castle with Spanish & Arabic influences
The town of Sintra was a small little town with cute little trinket shops, windy roads, and no trespassing areas that of course we just had to explore ;)
America, step up your game and start building castles!