Learn Polish: Dwudziesty trzeci rząd jest na górze. - The twenty-third row is at the top.

In Polish, ordinal numbers act like adjectives. For compound numbers like 23rd, both words change their endings to match the noun they describe. Since rząd (row) is a masculine noun, both dwudziesty (twentieth) and trzeci (third) are used in their masculine forms.

If I want to talk about a feminine noun, like the 23rd street (ulica), do I change both parts of the number?

Yes, exactly! Because both parts have to match the noun's gender, you would change both words to their feminine forms: dwudziesta trzecia ulica.

Doesn't the word rząd usually mean "government"?

It does! However, rząd is a word with multiple meanings. While it frequently means "government", it also means a "row" of seats, plants, or data. The context here (being "at the top") makes it clear that we are talking about a row.

Why is it na górze instead of na góra?

The word góra (which means "mountain" or "top") changes its ending to -rze because of the preposition na (on/at). When na describes a static location (where something is), the noun that follows must take the Locative case. The phrase na górze is a very common fixed expression meaning "at the top" or "upstairs".