Learn Farsi: این بنا یکی از معروف‌ترین یادبودهای شهر است. - This building is one of the most famous monuments of the city.

The phrase یکی از means one of. It is followed by the superlative adjective معروف‌ترین (most famous), and then the plural noun یادبودهای (monuments). Notice that because معروف‌ترین is a superlative, it comes before the noun it describes, rather than after it like a standard adjective.

Why is there an Ezafe on the end of monuments, but not after the superlative adjective?

Superlative adjectives ending in -ترین precede their nouns and do not need an Ezafe to connect to them. The Ezafe you see is the ی on یادبودهای, which connects monuments to شهر (city) to mean monuments of the city.

Could I use a singular noun after the superlative here, like in some other Farsi structures?

Not in this specific construction. Because you are using یکی از (one of), logic requires a plural group to select from, just like in English. You must use the plural یادبودها (monuments), not the singular یادبود.

What is the difference between using بنا and ساختمان for building in this context?

While ساختمان is the everyday word for a standard building like an apartment or office, بنا has a more formal and historical tone. It is used specifically for significant structures, monuments, or historical architecture, making it the perfect choice for this sentence.