Το ανέβασμα των τοιχωμάτων αρχίζει μετά το κεντράρισμα.

Because το ανέβασμα is a verbal noun: it turns the action to raise / lifting / raising up into a thing or process.

So instead of saying something like they raise the walls, Greek here talks about the raising of the walls as a stage in a process.

This is very common in technical, formal, and instructional Greek:

• το ανέβασμα = the raising / lifting
• το κεντράρισμα = the centering / alignment

The sentence therefore sounds more like a description of procedure than a normal everyday action.

Because ανέβασμα is a neuter singular noun, and Greek nouns normally take an article much more often than English nouns do.

Here:

• το ανέβασμα = the raising
• το κεντράρισμα = the centering

Also, nouns ending in -μα are very often neuter:

• το πράγμα
• το γράμμα
• το ανέβασμα
• το κεντράρισμα

So το is the correct article for both of those nouns.

Ανέβασμα comes from the verb ανεβάζω, which means to raise, lift, bring up, and in some contexts even to upload.

As a noun, ανέβασμα means raising, lifting, or putting up, depending on context.

In this sentence, because of των τοιχωμάτων, it means something like:

• the raising of the walls
• the building up of the walls
• the lifting/erection of the wall sections

So it refers to a process or stage, not to a person doing the action.

Because it is in the genitive plural, and it means of the walls.

Breakdown:

• το τοίχωμα = the wall / wall surface / side wall
• plural nominative: τα τοιχώματα
• plural genitive: των τοιχωμάτων

So:

• το ανέβασμα των τοιχωμάτων = the raising of the walls

The genitive here shows what is being raised. This is very common after verbal nouns in Greek:

• η κατασκευή του σπιτιού = the construction of the house
• το άνοιγμα της πόρτας = the opening of the door
• το ανέβασμα των τοιχωμάτων = the raising of the walls

Because the subject is singular.

The subject is not των τοιχωμάτων. The subject is the whole noun phrase:

• Το ανέβασμα των τοιχωμάτων

The head noun there is ανέβασμα, which is singular, so the verb must also be singular:

• Το ανέβασμα ... αρχίζει = The raising ... begins

A common learner mistake is to look at τοιχωμάτων and think the verb should be plural, but that noun is inside a genitive phrase and is not the grammatical subject.

It is in the accusative.

In Modern Greek, μετά normally takes the accusative when it means after:

• μετά το μάθημα = after the lesson
• μετά τη δουλειά = after work
• μετά το κεντράρισμα = after the centering/alignment

So here:

• το κεντράρισμα is accusative singular
• it looks the same as the nominative because it is a neuter noun

That is why the form is το κεντράρισμα and not something else.

Κεντράρισμα comes from κεντράρω, meaning to center, to align, or to bring into the middle/into proper position.

So το κεντράρισμα means:

• the centering
• the alignment
• possibly the positioning, depending on the technical context

In a construction or technical sentence like this, it usually refers to a preparatory stage done before the next step begins.

Yes, often there is.

• ο τοίχος usually means wall in a general, everyday sense
• το τοίχωμα often sounds more technical, and can mean a wall surface, side wall, or wall section

In technical or construction language, τοιχώματα may refer to structural walls, side walls, or vertical surfaces rather than just ordinary room walls.

So this sentence sounds more specialized than if it had used τοίχοι.

Because Greek uses the definite article more often than English, especially with:

• abstract nouns
• process nouns
• technical descriptions
• noun phrases with genitives

So Greek naturally says:

• Το ανέβασμα των τοιχωμάτων αρχίζει μετά το κεντράρισμα

Where English might drop some articles depending on style:

• Wall raising begins after centering
• The raising of the walls begins after the centering/alignment

Greek generally prefers the articles here.

Yes. Greek often allows both a nominal style and a verbal style.

A more verbal rephrasing might be something like:

• Αρχίζουν να ανεβάζουν τα τοιχώματα μετά το κεντράρισμα. = They begin to raise the walls after the centering.

But that version introduces an implied subject such as they, and it sounds less like a formal process description.

The original sentence is more impersonal and procedural:

• Το ανέβασμα των τοιχωμάτων αρχίζει μετά το κεντράρισμα. = The raising of the walls begins after the centering.

So the original is more suitable for manuals, instructions, or technical writing.

The sentence follows a very natural Greek order:

• Το ανέβασμα των τοιχωμάτων = subject
• αρχίζει = verb
• μετά το κεντράρισμα = time expression / prepositional phrase

So literally:

• The raising of the walls begins after the centering

Greek word order is flexible, but this order is straightforward and neutral. It presents:

1. the process,
2. what happens,
3. when it happens.

The stress is important:

• Το ανέβασμα → a-NE-va-sma
• των τοιχωμάτων → ton ti-kho-MA-ton
• αρχίζει → ar-khi-ZI
• μετά → me-TA
• το κεντράρισμα → to ken-DRA-ri-sma

A few useful notes:

• χ in αρχίζει and τοιχωμάτων is the Greek sound like a soft h/ch, not an English k
• αι in μετά is pronounced e
• οι in τοιχωμάτων is pronounced i

Not usually. It sounds more like:

• a manual
• an instruction sheet
• a technical description
• a construction or engineering text

That is mainly because of the noun-heavy style:

• το ανέβασμα
• το κεντράρισμα

In everyday conversation, speakers might prefer a more verbal and less formal way of expressing the same idea. The original sentence is correct and natural, but it belongs to a more formal or technical register.