There is a popular idiom in Russian for describing a really crowded place: "(there's) no room for an apple to fall" ("яблоку негде упасть").
I struggle to think of anything similar in English, and the dictionaries I consulted were of no help, simply translating it as "crowded" or not even including it at all.
The context would be something and anything along the lines of
The place was so crowded that [X].
The room was full to the extent that [Y].
The street/square was [Z].
At the top of the hat charts, there is [no room for an apple to fall].
Which is to say, I am not married to any sentence structure in particular — I'll gladly rewrite from scratch to use a vivid and idiomatic adjective or noun, word or phrase, metaphor or saying, rather than try and shoehorn it into a sentence it does not feel itself welcome in.
Best Answer
If it is extremely crowded, you can say "packed like sardines in a can" or just "packed like sardines" or "packed." This comes from the way sardines are tightly packed into cans when canned for eating:
Strictly speaking, some people will object to this usage: both the place and the people in it can be said to be packed, but only the people can strictly be packed like sardines since the sardines are inside the can and the people are inside the crowded place. However, colloquially people will use the phrase in both senses. Also, most people just say packed: