Learn Spanish (Latin America): El banco está en la ciudad.

está comes from the verb estar, which is used to talk about locations (where things are). Even though a bank is a permanent building, Spanish always uses estar for the physical location of people, places, and things. You would use es to describe what the bank is, but está to say where it is.

Does en always mean "in"?

en is a very useful word that can mean "in", "on", or "at" depending on the context. Here, because we are talking about being located within a boundary, it naturally translates to "in".

I thought nouns ending in a consonant were usually masculine. Why is it la ciudad?

While it is true that many words ending in consonants are masculine, words that end in -dad (like ciudad or universidad) are almost always feminine in Spanish. That is why we use the feminine word for "the", which is la.

How important is the accent mark on está?

It is extremely important! está (with the accent mark) is the verb meaning "is". If you write esta (without the accent), it changes the word to mean "this" (as in esta ciudad for "this city"). The accent mark also tells you to put the stress on the final syllable when speaking.