Woocommerce: change lable of City in checkout page

Hello
I am changing the label and place holder of fields in checkout page, I am able to change few of them but unable to change the label adn placeholder for city. I am using the below code

add_filter( 'woocommerce_checkout_fields' , 'custom_override_checkout_fields' );

function custom_override_checkout_fields( $fields ) {

// change label and place holder
$fields['shipping']['shipping_first_name']['placeholder'] = 'Guest First Name';
$fields['shipping']['shipping_first_name']['label'] = 'Guest First Name';
$fields['shipping']['shipping_city']['placeholder'] = 'Deperature City/Town';
$fields['shipping']['shipping_city']['label'] = 'Deperature City/Town';

return $fields;
}

Its working fine for firstname and last name but not working for city/town

Thanks in advance