You may use PhoneApplicationService.Current.State to store and retrieve data between pages. For example in Page A:
Place loc = new Place();
//fill the Place properties
PhoneApplicationService.Current.State["place"]=loc;
//Navigate to Page B
In Page B inside the OnNavigatedTo:
Place place = PhoneApplicationService.Current.State["place"];
You may want to add some Exception catching in there and make sure the key "pins" exists in the State collection.
Yo can also use a public property in the App.xaml.cs.
public Place place {get;set;}
In Page A:
var obj = App.Current as App;
obj.place = aPlace; //assumming aPlace is already created
In Page B, OnNavigatedTo:
var obj = App.Current as App;
aPlace = obj.place; //assuming you have aPlace declared before