Database: real_estate_rentals
Question: Return the cities in which there exist properties that have swimming pools.
SQL:
SELECT T2.town_city FROM Properties AS T1 JOIN Addresses AS T2 ON T1.property_address_id  =  T2.address_id JOIN Property_Features AS T3 ON T1.property_id  =  T3.property_id JOIN Features AS T4 ON T4.feature_id  =  T3.feature_id WHERE T4.feature_name  =  'swimming pool';