Learn Hardcore Hungarian: Ma a könyvtárba megyek a park helyett, és ott maradok tovább. - Today I go to the library instead of the park, and I stay there longer.

-ba/-be is the illative case: “into” a place (movement). You use -ba after back vowels (a, á, o, ó, u, ú) and -be after front vowels (e, é, i, í, ö, ő, ü, ű). Since könyvtár contains the back vowel á, it takes -ba: könyvtárba = “into the library.”
Compare: házba (into the house), kertbe (into the garden), üzletbe (into the shop).

Why are there articles (a) before könyvtárba and park? Can I drop them?

Hungarian uses the definite article a/az more often than English. With places and institutions:

With article: a könyvtárba megyek = I’m going to the (specific) library.
Without article (institutional/generic): könyvtárba megyek = I’m going to the library (as an institution, not necessarily a specific one).
Both are possible here. With park, both are also possible, though the article is more common if a specific park is meant: (a) parkba megyek.

Is the word order natural? Would Ma a park helyett a könyvtárba megyek be better?

Both are grammatical. Hungarian word order highlights the element immediately before the verb (focus).

Ma a könyvtárba megyek a park helyett puts focus on the destination: “It’s to the library that I’m going.”
Ma a park helyett a könyvtárba megyek foregrounds the contrast (“instead of the park”) and is often felt as a bit more natural here.
Either is fine; choose based on what you want to emphasize.

How does helyett work?

helyett is a postposition meaning “instead of.” It follows the noun it governs, which stays in its base form:

a park helyett a könyvtárba megyek = I’m going to the library instead of the park.
You can also use the pronominal form helyette (“instead of it/him/her”): Helyette a könyvtárba megyek.

How do I say “instead of going to the park,” not just “instead of the park”?

Two common options:

Noun phrase: a parkba menés helyett a könyvtárba megyek (instead of going to the park…).
Clause with ahelyett, hogy
- conditional: Ahelyett, hogy a parkba mennék, a könyvtárba megyek.

Why is it könyvtárba megyek but “I (will) stay there” could be a könyvtárban maradok?

-ba/-be = movement into: a könyvtárba megyek (I’m going into the library).
-ban/-ben = location in: a könyvtárban maradok (I’m staying in the library).
In the sentence, ott maradok (“I’ll stay there”) refers back to the library. You could say és a könyvtárban maradok tovább for clarity.

Why is it ott maradok and not oda maradok?

Hungarian distinguishes static vs. directional “there”:

ott = there (static): Ott maradok (I’ll stay there).
oda = (to) there (direction): Oda megyek (I’m going there).
So: a könyvtárba megyek (or oda megyek), and ott maradok.

What nuance does tovább add in ott maradok tovább?

tovább means “longer/further” and is comparative by nature—usually “longer than (something).” Here it implies “longer than usual/than planned/than if I went to the park,” understood from context. If you want a non-comparative “for a long time,” use sokáig: ott sokáig maradok.

Do I need to say what it’s “longer than,” e.g., with mint?

Only if you want to make it explicit:

Tovább maradok, mint tegnap. = I’ll stay longer than yesterday.
Without mint: tovább maradok leaves the comparison implicit (context supplies it).

Is ott maradok tovább or ott tovább maradok better?

Both are correct; the difference is emphasis:

ott maradok tovább puts the main emphasis on the place (ott).
ott tovább maradok puts the main emphasis on tovább (“longer”).
If you want to stress “longer,” many speakers prefer ott tovább maradok.

Could I say bemegyek a könyvtárba or elmegyek a könyvtárba instead of megyek?

Yes, with nuances:

megyek a könyvtárba: neutral “going to the library.”
bemegyek a könyvtárba: emphasizes entering (going in).
elmegyek a könyvtárba: emphasizes leaving (from here) to go to the library.
All are natural; choose based on the aspect you want to highlight.

Why is the present tense used (“I go,” “I stay”) when it refers to today/near future?

Hungarian commonly uses the present tense for near-future plans when there’s a time adverbial (ma, “today”). Ma a könyvtárba megyek naturally means “I’m going to the library today.” A future construction with fog is possible for emphasis: Ma a könyvtárba fogok menni.

Is the comma before és necessary?

Yes. In Hungarian, a comma is normally used between two independent clauses linked by és. So …, és ott maradok… is standard punctuation.

Why isn’t it a parkba helyett?

Because helyett is a postposition that takes a base-form noun: a park helyett. If you want to say “instead of going to the park,” then you add a verbal noun or clause: a parkba menés helyett / ahelyett, hogy a parkba mennék.

Does ott definitely refer to the library here?

Yes, by default it refers to the most recently mentioned relevant location, i.e., the library. If there could be ambiguity, you can be explicit: … és a könyvtárban maradok tovább.

Any spelling pitfalls with helyett?

Yes: it’s helyett with double t. helyet (one t) is the accusative of hely (“place/seat”), e.g., Kérek egy helyet (“I’d like a seat”). Here you need the postposition helyett (“instead of”).