'urlManager' => [
        'enablePrettyUrl' => true,
        'showScriptName' => false,
        'rules' => [
            '<controller:w+>/<city:d+>' => '<controller>/view',
            '<controller:w+>/<action:w+>/<city:d+>' =>
                               '<controller>/<action>'
        ],
    ],

echo Html::a('<h4>'.$cities[$i].'</h4>', ['/ads/browse',
             'city'=>$cities[$i]], ['class'=>'btn buttonCity']);