it says in noise that the moon is encapsulated into the gigastructure (i just invented that to describe "all megastructures" - or is it, what everyone keeps calling "chaos"?) and in blame killy climbs up a 3000 kilometres high staircase, crosses a hollow sphere 143km in diameter and in the last chapter he uses some elevator that may go up some more hundrets if not thousands of kilometers (not to mention the thousands of levels he already passed inside the first megastructure). if the gigastructure is that big, would there still be any uncovered space on earth like the last log suggests?

No way is there any uncovered space on Earth.

I took the last log (with the moon and the sleepy people and whatever) to take place somewhere inside a program, kind of like how Musubi appears in a room in NOiSE to talk with the Safeguard guy. Or maybe it's more like that space Cibo went in to in vol. 4 (the pages in color.) Anyway, some program or another.

And if you diagree with me (Like apparently everyone else likes to do!!) then at least, it takes place on a planet that's not Earth.

Sorry to disagree once again, but it seems to me that it is a real place, and it's not necessary for it to not be Earth. I think that the oceans were basically transported to the outer reaches of the megastructure perhaps as some sort of cooling system (as some people who think the whole thing is a Dyson sphere suggested) or maybe the infection that destroys Net Genes doesn't work in water so the GA or somebody else took all the water up there so there was a safe haven, making it possible to breed another Net Gene Carrier (which is what happened). Or maybe Nihei just thought it would look cool to have the whole planet covered in water

I'd bet that the moon and the earth and all the other unlucky satellites that fell within the megatructure's reach all got completely ground up into base metals and elements for building material. As planets they likely dont exist anymore and unprocessable parts were shifted and stored to various parts of the megastructure (Vol.8)

Nihei said in the artbook that the structure extends to Jupiter's orbit, like you said. The sun can't be seen from space because the structure surrounds it entirely. But there has to be a sun, because they have to get energy from somephere. The whole concept of the Dyson Sphere is to be able to use maximum energy from the sun.

-Jenshin

A Dyson sphere, if I understand correctly, should be like a shell, anyway a think layer around the star. But the strucutre described in Blame has thousand of levels, and if it extends all around the sun, the mass should be incredible. I wonder if people can bear the gravity attraction on the external levels.

I personally think that Nihei changed his mind during the past years : in the first volumes the City seems more like a gigantic building. Killy mentioned also a 'Level 5000' in the depths of the City.
Now, if the megastructures extend from Earth to Jupiter, the number of levels should be much higher than 5000.

I am just confused with one thing in Blame! world - in the beggining when Killy is reading book with that girl they look up and she says: It is getting dark What are they talking about - is ending up like they are seeing a sun set above the megastructure! That would meen that they are on the opposite edge of the City! So I think direction of his adventure can`t be determinated... it is just too much complicated...
But still there isn`t any explanation about that "sunset" they saw...

That's not a sunset. Those are lights dimming. A sunset wouldn't happen all at once like that, and it would be brighter at one end toward the sun and darket at the other. The way Nihei emphasizes that one spot of light points to it being an abrupt, electrical dimness. Although I can't really tell, those slits might all be long lights themselves.

-Jenshin