yourCity.php

<?php
// определение ip
if (!empty($_SERVER['HTTP_CLIENT_IP']))    {
    $ip=$_SERVER['HTTP_CLIENT_IP'];
}elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR']))    {
    $ip=$_SERVER['HTTP_X_FORWARDED_FOR'];
}else{
    $ip=$_SERVER['REMOTE_ADDR'];
}
// https://dadata.ru/
$api = '05ede21fd19ece0776055555c39201qwqe4ead36';
$key = 'f1983881d43d55555529155df23428ccff8abfae';
// создание cURL
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'https://suggestions.dadata.ru/suggestions/api/4_1/rs/detectAddressByIp?ip='.$ip);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "GET");
$headers = array();
$headers[] = 'Accept: application/json';
$headers[] = 'Authorization: Token '.$api;
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

$result = json_decode(curl_exec($ch), true);
$city   = $result['location']['data']['city']; // эт наш город =)
if (curl_errno($ch)) {
    echo 'Error:' . curl_error($ch);
}