Eco you cool 5 tables.
JOIN is not for this, you just need to combine 5 queries, the UNION operator
(SELECT id, title, mini_img, text, price, adress FROM kvartira WHERE city = '$cityS') UNION (SELECT id, title, mini_img, text, price, adress FROM kvartira WHERE city = '$cityS') UNION (SELECT id, title, mini_img, text, price, adress FROM domkat WHERE city = '$cityS') UNION (SELECT id, title, mini_img, text, price, adress FROM garage WHERE city = '$cityS') UNION (SELECT id, title, mini_img, text, price, adress FROM commercial WHERE city = '$cityS') UNION (SELECT id, title, mini_img, text, price, adress FROM zemelnyi WHERE city = '$cityS')
By the way, I venture to ask, why do you need 5 identical tables? It can all merge into one and add the type field, where and write kvartira, domkat, garage, commercial, zemelnyi