I arrived at a large house/ mansion. It was nighttime, so I wasn't able to make out the details of the house clearly. It was a low-lying house, maybe two stories. It was built in the 70's, reminiscent of a sprawling rancher. The paint was a dark brown, almost black. There may have been one of those odd cutout circles in the roof, common of larger buildings from that era, and probably it had one or two dome skylights - the ones from the 70's that were opaque with an off-white color; faded plexiglass. There was a driveway and a large grassy front yard in front of the house - gravel drive with a terraced rock garden leading up to the house. Round moon-shaped street lights on top of a cast iron gate were placed at odd intervals, not really enough to light up the house, but enough to find your way.
I entered the house by the front door, and there was a sunken living room that seemed more like a furniture showroom because it was so large. Couches marked off square meeting spaces; the decor was generally muted colors, light gray, mid-to late- 80's furniture. Some had coffee tables in the interior space, others had side tables. The overall feeling was conservative. The lighting was dim, not warm, but not uncomfortable.
Along the walls were alcoves that at first seemed like the "lighting department" of the furniture showroom, but as I looked closer there was more to it. The far wall from the front door was a square archway that led to another "living room" / meeting area. I went over to look through it, and I could see that there were many more living rooms (similar spaces to this) going off in the distance. This didn't seem to bother me - it was something I took for granted. To the right of this entrance, there was a lighting display. A light at the top of the display was like the full moon. Below that, a miniature mountain, with a stream running down the mountain. I was reminded of a Japanese painting of a mountain, that had been turned into something 3-D. I was also reminded of the mountain in Close Encounters of the Third Kind. All of this sat on a shelf placed at about waist-height. Light and dark gray on the walls, done in a tasteful/conservative way.
There were a few people in the "living room" area with me, it felt like a reception or party. It felt like there were more people still to come. The few that were there were chatting idly. As with any event like this I didn't talk to anyone - it's usually possible for me to be alone in a room full of people. That didn't bother me, though. It was enough to just be there.
There were stairs to the right of the front door leading up to what I assume would be the bedrooms, bathrooms, etc. of the house. I found myself in a large bathroom. It was completely tiled with light yellow tiles, it felt like a room in a hospital. In the center of the bathroom was a raised tiled platform with a shower head and a drain, and a hospital-green curtain that went right around the perimeter of the platform, hanging from a chrome railing. I decided to have a shower, and when I turned on the shower there were additional jets to the right and left of the shower head, kind of like a garden sprinkler. I thought this was a silly / unnecessary feature. At this point I thought that I was in my sister's house, though I never met her in the dream. It was just something I knew.
After I finished my shower I wrapped a beige towel around me, and for some reason thought it was a good idea to head back to the living room like this. Perhaps it was for the purpose of shocking the party-goers, a practical joke, and I pretended to shriek as the towel exposed part of my leg. This is not something I'd normally consider doing.
After that I headed back upstairs to get dressed, and that was the end of the dream.