Why didn't you drop by my place if you came around here.
Drop by my place; 私のところに立ち寄る
Come around here;ここら辺に来る
ここら辺に来たんだったら、私の家に立ち寄ってくれれば良かったのに。
Why didn't you...?
Why don't you...?の過去形です。
「なんでしてくれなかったの?」
=「---してくれれば良かったじゃないの。」
My place;は自分の場所。これは文脈次第で自分のオフィスにでも、自分の家にでもなります。
You were so close to my house, too bad you didn't stop by.
You were in the neighbourhood, you should have dropped in.
この場合、次のような言い方ができますよ。
ーYou were so close to my house, too bad you didn't stop by.
「そごくうちに近かったから、寄ってくれなくて残念だよ」
ーYou were in the neighbourhood, you should have dropped in.
「近所にいたんだ、寄ってくれたらよかったのに」
立ち寄ることは to stop by や to drop in を使って言えます。
ご参考まで!