main.dart

class MyApp extends StatelessWidget {
 // This widget is the root of your application.
 @override
 Widget build(BuildContext context) {
   return MaterialApp(
     title: 'Firebase for Flutter Demo',
       home: Scaffold(
         body: StreamBuilder(
           stream: FirebaseFirestore.instance.collection('places').snapshots(),
           builder: ( BuildContext ctx, AsyncSnapshot<QuerySnapshot> snapshot){
             if(snapshot.connectionState == ConnectionState.waiting){
              return Center(child: CircularProgressIndicator(),);
             }
             final documents = snapshot.data.docs;
             return ListView.builder(
              itemBuilder: (ctx, idx) {
                return Padding(
                  padding: const EdgeInsets.all(8.0),
                  child: Text(documents[idx].data()['city']),
                );
              },
             itemCount: documents.length,
             );
           },
         ),
         floatingActionButton: FloatingActionButton(
         child: Icon(Icons.add),
         onPressed: () {},
         ),
       ),
     );
   }
}