Exceptional + generous, how to proceed?

Since I probably want to build next year or at the latest the year after next, I am now starting to deal with the topic of house construction a bit more intensively and hope to get some suggestions or answers to my questions.

The plot (2400 sqm) is available, about 40 km south of Hamburg. I am not allowed to build two stories, otherwise everything is permitted.

Basically, I want two things: extraordinary architecture and very spacious and open construction.
- Point 1 is very important to me. I want to stand in front of my house and be excited by it every day. It should definitely not be off the shelf. I have many pictures of houses from newspapers and the internet that I like. I just never know what such houses cost and how big they have to be at least to realize them. I don’t yet know exactly what I want.
- Point 2: I am sure there will be a lot of criticism or comments that it is way too big, but I am planning about 400-500 sqm of pure living space. Currently, I live alone in 190 sqm and it is not too big for me either.
Rough idea:
Ground floor: 100 sqm living room should be the center of the house. Ceiling height over 2 floors. Kitchen 40 sqm, dining room 30 sqm, bathroom 15 sqm, guest room 20 sqm, utility room 30 sqm, office 25 sqm
1st floor: bedroom 35 sqm, bathroom 30 sqm, dressing room 30 sqm, small office 15 sqm (all en suite)
3 children's rooms each 30 sqm, full bathroom 20 sqm
Currently, the areas on the ground floor and first floor do not yet fit, but these are only my first considerations without having spoken to an architect.

Unfortunately, there is relatively little information on the internet about properties of this size. So prices, floor plans, pictures, etc.

How should I proceed best now? I have 2 architects in my immediate area who have already built fairly unusual reference projects and whom I like. I wanted to make appointments with them soon. Does anyone perhaps have recommendations for architects from Hamburg and the surrounding area who can realize something like this? An architect who usually designs/oversees more classic single-family homes is probably not the right contact. Where can I find an architect suitable for my building project?

All trades are to be awarded individually. Would the architect also handle the tendering, negotiation, and acceptance, or should one commission a second person for that?

How much time should I plan for the entire project? 3-6 months planning and then another 6 months construction time or is that too much or too little?

And now the perhaps most difficult question: What kind of budget should I expect? House completely ready to move into. So kitchen, floors, painting work, lamps for all rooms, ancillary construction costs but without garage, furniture, and outdoor facilities - these come separately.
The question is of course very difficult to answer generally. You can spend €5,000 on a kitchen but also €200,000.
It should be very upscale or high-quality equipment but I don’t need golden faucets. Can I manage with one million?
I am grateful for any suggestions or experience, gladly also by PM.

You are not allowed to build two stories but are planning with 2 floors?

I consider one million to be too tight a budget - without being specifically luxurious, you can easily sink 1.5 million or even 2 million into such a property - and that without golden faucets.

However, one must say: just having a lot of square meters does not make a house spacious - there is more to it. Do you have special representation plans, aiming for a living area of 100 sqm? In a house of this size, one expects each bedroom to have its own bathroom, possibly the children sharing one bathroom between two. Many couples also prefer separate bathrooms - each then somewhat smaller. A purely shower bathroom is still spacious at 12 sqm - a bathroom with a freestanding tub plus shower can be 20 sqm.

Hallways should rather be corridors. You can also plan enough utility rooms so that you get plenty of storage space without getting lost. Possibly, I would also include a granny flat / servant / nanny quarter. Enough garage spaces (4-6 cars plus space for sports equipment) ... yes, that adds up.

Choose a very good architect - preferably a woman who also thinks somewhat practically - as well as a very good and experienced site manager who oversees the trades, handles the tenders, etc. - this rarely comes together in the same person. However, with a good architectural firm, you can find both. Additionally, a building expert who accompanies the construction - this way, the roughest botch jobs are avoided and the construction is most likely to run smoothly.

In addition to Nofret:
regarding the requirements, I would directly involve an interior architect / lighting planner in the planning. Both to actually achieve the desired spatial effect and to plan the light outlets. And I would also have a media room set up (or have it set up) with a projector, surround sound...
I don't think 1 million will be enough.
I urgently need to play the lottery again.

: You can easily build 2 floors, even if only single-story construction is allowed. If the first upper floor has less than 66% of the ground floor area, it is not counted as a full floor. Due to the planned living room spanning 2 floors, this is relatively easy to achieve. For example, 300 sqm ground floor and 200 sqm 1st upper floor.

and Malli: There were already some very good tips, thanks!

A granny flat, one bathroom per bedroom, 6 garage spaces falls under the category of "unnecessary luxury" for me. But of course, that is a matter of opinion. I have high standards for kitchen, bathroom, technology, and lighting. On the other hand, I don’t need parquet flooring that costs 300€ per sqm.
In fact, it’s not just about the square meters, but also about the layout and the furnishings, so that a house of this size really comes into its own. Of course, it’s pointless if you have a 30 sqm bedroom and there’s only a bed and a nightstand in it.

Does anyone have ideas or suggestions for an architecture firm (in Hamburg + surroundings) that ideally offers everything from a single source?
Is there any other way to get information (i.e., plans, pictures, costs) about similar projects? Of course for a fee. I seem to remember that somewhere on the internet you could buy this information about commercial properties. Unfortunately, I can’t find anything quickly.

I am not allowed to build two stories, otherwise everything is permitted.

How many m² of the plot may be built on according to the development plan or floor space index (is there one)? We thought with over 1300m² plot and a floor space index of 0.25 we wouldn’t have any problems and now it’s tight after all. Eaves height or something similar is also not specified?

I just never know what such houses cost and how big they have to be at least to realize them. I don’t yet know exactly what I want.

Architects can help you best with that. Anyone who wants something individual tailored to their needs will hardly find themselves again in existing floor plans/pictures of other buildings.

Unfortunately, you can find relatively little information on the Internet about objects of this size. Like prices, floor plans, pictures, etc.

Because the clientele rarely exchange information about their villas on the Internet. Why does the price matter at all? As already mentioned, the price ranges for properties of this size are enormous. Nevertheless, the architect can also help here. Alternatively, you can look at what existing properties of this size cost.

All trades are to be tendered individually.

Why?

How much time should I plan for the whole project? 3-6 months planning and then another 6 months construction time or is that too much or too little?

To my knowledge, 6 months is about the standard for a single-family house in solid construction. Other construction methods might also be completed in 4-5 months. Given the size, I consider 6 months optimistic. Ultimately, it depends on how many craftsmen are working on the construction site.