I’m just now watching Cleopatra (5-1/2 hours on TV, was 3-4 in the theatres, depending on which cut you got)
And all the palaces are shiny and new. The big 50’s-60’s epics were all like that.
Newer movies tend to show every castle as well worn.
But I wonder which would be more authentic.
That’s an interesting question. I would expect a palace in Egypt to be cleaner and shinier than a castle in England or France, just because of the drier climate. Not to mention slave labor to keep everything spiffy.
I think the first historical (Middle Ages) movie I saw that had a realistic look was The Lion in Winter. The place was dark, gloomy, muddy, and dirty. You could tell there was no central heating. 
Actually, very frequently [if you look at illuminations, and archeological evidence] walls were coated in plaster, interior walls were coated in plaster and painted in bright colors and walls were covered with woven cloth that may have some embroidery or simple patterns woven in for less expensive venues, and elaborate embroideries or woven tapestries for the high end royal palaces.
A perfect example of this is a few of the earlier french chateaux such as Angers. They have a couple of rooms and part of teh exterior restored. Fascinating.
I think Cleopatra’s palace may have been new. I vaguel remember reading that the one that was recently discovered underwater was either built by her or built by her father. So, it might have looked kinda shiny during her lifetime.
Thanks, aruvqan. The buildings would still be cold, wouldn’t they? The tapestries would make the walls more attractive and might provide some insulation from the damp, but I imagine if you moved five feet from the fireplace, you’d feel a chill.
Sometimes they used charcoal braziers placed at various locations around the room to add a little extra heat. If you’ve ever been to an patio party in the fall where your host has little firepots placed around, you’re probably getting a pretty good comparison. Rooms that had them probably wouldn’t have been toasty, but they’re tolerable, especially if you’re wearing multiple layers. You can walk up to them and warm your hands, anyway.
Clothing … you would be amazed how comfortable you can be wearing a houpeland. I wear medieval and renaisance clothing frequently [member of the society for creative anachronism] and the clothing is surprisingly warm when made of teh proper fabrics. I make a lot of my clothing in the wrong [lightweight cotton and linen] fabric to keep from roasting in the winter in modern heated buildings. I can stand outside in perfect comfort in snow and chat with my friends who are smoking.
Hey, in Spain that was considered an advantage! We spend more time under a sun of molten lead than under snow, even in the Meseta. Many castles had a single fireplace, at the kitchen. Fireplaces would often be at the lower floors only and have the flues set in such a way that they served as radiators.
Windows would get heavy curtains, to be closed mostly at night, keeping out the chill; also wooden shutters, generally on the outside. Sometimes they’d be closed with a sheet of thin alabaster or oiled parchment, but this was rare. Dampness isn’t much of a problem in most of Spain, but wind can be (which explains why two of the biggest wind-power-plant-building companies are from Spain). Windows would be placed trying to maximize breeze for the summer. In winter, if the room is still breezy in spite of the curtains… get a second set of curtains on top of that one, you silly you!
And of course dressing like an onion helps
Depends on the circumstances - something like the Parthenon in Greece, or most of the major public buildings during the Roman Empire would have been kept up rather nicely. But they were meant to be public spectacles, shiny and bright in a world that most definitely was not. A working Roman fort on the frontier might be nice, but would be far more practical and show more wear and tear than someplace being kept up by a thousand slaves. And when finances got tight, all that cosmetic and preventive maintence budgeting was canceled.