Noble residential house in Roman style - Who builds something like this?

Fortunately, there are development plans. I wonder what cities and villages would look like if everyone built whatever they liked?! I already find it disturbing when a log cabin suddenly stands between the plastered facades.

My dad has a neighbor like that. He has the garden full of life-sized statues, columns, and amphorae. The neighbor next to him counters with a bunch of garden gnomes and glowing flowers. If aliens are watching us, they must think we're all crazy here. :D

I do find it disruptive when a log cabin suddenly stands among the plastered facades.

Ironically, you find this kind of punk-style mishmash especially in those housing areas where the local council has gone to great lengths to make sure all roofs look exactly like that of the shooting club clubhouse. Grevenbroich is everywhere, white to take note ;-)

Roman architecture was (besides reasons of demonstrating wealth) the way it was because this architecture worked well in the Roman climate. That might still fit quite well in the southern Palatinate vineyards, but here in northern Germany it would seem strange and probably wouldn't work very well, I believe.

So financially, you have to plan well over a million for such a project. More likely rather 2 - 3 million EURO.

perhaps better to build something more neutral and create your Roman Empire in the garden :)

Someone here built something like this (or is still building it), mixed with modern elements. It looks quite impressive, but somehow some parts clash. It is surrounded by such columns with the typical flat triangular roofs above (I have no idea what the technical terms are here). Behind them, huge glass surfaces, marble facades (I think it is marble), roof terraces with Roman/Greek balustrades.. etc. The house has 3 full floors and dimensions of about 20x30m, I would estimate the ground floor ceiling height at 5m. It has been under construction for at least 6 years. So you need to have time.

Wow. I would be interested in seeing that in person. What kind of character do you think resides there? I can think of quite a few prejudices.

I expect, despite all the splendor, to keep the size as modest and small as possible, since I could certainly never afford a large villa

What is important to me here is that it is really made from noble materials (Corinthian columns, frescoes, marble floors, mosaics, sculptures, etc.)

However, even on a small plot, the noble material you mention has to be paid for. Even "material" alone is a major cost factor, even if only used in small amounts.
For example, with normal tiles: one person can afford 90€ or 130€ porcelain stoneware tiles, another only 20€ but still pays a lot for their house. Where do you think your wishes will end up?
When I think of embellishments or putti, they only work as a whole. I cannot imagine designing a standard villa with a glamorous entrance; for me, it would be intentional but not skillful. Personally, I don't like it either.

Definitely, early on I had the dream to enable an own house in classical Roman style at some point during my life.

I would say: you can like many things, you can have a penchant for this and that, but you don't have to have everything.
That's what a hobby is for. Many people join medieval clubs because they have an affinity for that era. Spending your vacation in a tent or hut as they had back then also has its charm. But very few probably want to build their entire life around it ;)

I see the realization of your interest more in possibly designing a bathroom in a normal house to give you that flair.

Certainly there are many other styles that also have their charm, but I have always wondered why nowadays so little is actually built in that style.

That is clearly because every style has its time. And we simply no longer live in ancient Roman times.

I would be satisfied with a small building as a life goal, ideally a size that still allows for a small atrium with an inspiring garden.

An atrium is nice. I like courtyards.
However, with today's energy-saving regulations it is difficult, and with today’s building costs, a standard house is already the highest one can achieve in a lifetime.

Therefore, I can only advise you to live out your penchant in a hobby, with picture books, or through vacations. Everything else is far from any reality.

Of course, you can also design your garden later. On vacation, I have seen some misguided house plans with exactly these front gardens – personally, I always get eye strain from this implementation in such quantity and frequency.
An amphora in a rock garden can look very nice, but if it’s too much, it’s too much.