The Major Sights
Frommer's: Castelo dos Mouros, with description, hours, etc.
Virtual Portugal: Moorish Castle. Grainy images.
Frommer's: Palácio Nacional de Pena, with description, hours, etc.
Amazon. Pena Palace by Paulo Pereira, Jose Martins Carneiro (Scala Books, June 1999). I bought this one when I was over there. It's just about what you'd expect, a competent coffee-table book on the Pena Palace.
Pena Palace: Don and Linda Freedman's travelogue. A bit credulous:
"There are natural magnetic properties because of massive deposits of iron ore. You can go into a cave and your watch will stop. You can shut off your car at a particular point and feel the car being pulled uphill. We didn't experience this phenomenon but it is so recorded."
Quinta de Regaleira
Virtual Portugal: Quinta da Regaleira. Decent summary.
Frommer's: Quinta da Regaleira, with short description, hours, etc. The description hardly does it justice; it comes off as the smallest, least-interesting destination in Sintra. I'm not even sure the writer visited the place.
"Portuguese Man of Awe" Sunday Telegram (UK), August 29, 2004. Profile of Sintra and environs, with a good bit on the Quinta.
"Awesome or gruesome? I felt a bit like Indiana Jones as I passed through a huge revolving stone door and hopped on precarious stepping stones across a man-made subterranean lagoon."
Detailed information on the Quinta in Portuguese from a Masonic site. Detailed. Unfortunately, the Google translation doesn't handle the specialized terminology very well.
Detailed Portuguese page on the symbolism from a group of Portuguese Wiccans. Unfortunately, this page doesn't auto-translate.
Frommer's: Palácio Nacional de Sintra, with description, hours, etc.
Amazon. National Palace, Sintra by Jose Custudio, Jose Custodio Vieira De Silva, Vieira Da Silva.