Welcome to the Pena Palace in Sintra, which is just outside of Lisbon in Portugal. There are a number of things to see in Sintra (if you are going to Portugal you should spend a least a day there) but the most popular thing is the Pena Palace.
It's what many people think of when they think of a Castle, with it's classic 'rook' formatations and towers. It is perhaps a little more colourful than you were thinking, and that is largely because it's not a 'real' castle in the sense that it's not Medieval - if you want that go to the Moorish Castle just down the road. No this was actually a monastery in that time, and then in the mid 1800's King Ferndand bought what was left of the monastery and rebuilt it as a Summer palace of the royal family, A nice getaway not too far from Lisbon and up in the mountains for a little relief from the summer heat.
Now that is only 170 odd years ago, so there a plenty of familiar things in the palace, the rooms a logical to modern eyes, there are offices, and bathrooms and walk in wardrobes, so the inside a little like the seeing any historic house, but the outside is were the magic is.
The colours are amazing, we were lucky that we had pure blue skies for part of our visit, although it did cloud over for a while which was a whole other experience of literally being in the clouds in a castle..
This is how the architecture is described in Wikipedia - which I think explains why it's unlike anything else you will see. The Pena Palace has a profusion of styles much in accordance with the exotic taste of the Romanticism. The intentional mixture of eclectic styles includes the Neo-Gothic, Neo-Manueline, Neo-Islamic and Neo-Renaissance
Oh and as for tips for being a tourist, well there are people everywhere, you can see most of it without actually going 'inside' although the views are better from inside and there are less people around. I would choose the first or second tour slot of the day as you will then only have to wait for 10-20 minutes to get in. This means leaving Lisbon at like 7.30am in the morning. You can train to Sintra and then jump on a Bus, it's all pretty easy so you can certainly do it by yourself you don't need a tour. If you start at Pena Palace you'll be done with that by Lunchtime, so pop back into Sintra itself grab lunch and then see what else you have chosen.
All of these photos are taken by me to a Fujifilm X-T5 and a 16-80mm Zoom, which I find a fantastic 'can do anything lens' Looking at the focal lengths of these shots most are between the 30-60mm range (on full frame) so the standard 18-55mm lens from Fuji would likely do the job as well.
I love this place… good memories!