<?php
$xml = '<Sites>
    <Items>
        <Item>
            <id>1</id>
            <URL>https://m...content-available-to-author-only...e.com</URL>
            <Host>mysite.com</Host>
            <Folder>mysite</Folder>
            <Database>mysite_app</Database>
            <DBuser>mysite_app</DBuser>
            <DBpassword>pass</DBpassword>
        </Item>
        <Item>
            <id>2</id>
            <URL>https://m...content-available-to-author-only...e.com</URL>
            <Host>mysite.com</Host>
            <Folder>mysite</Folder>
            <Database>mysite_app</Database>
            <DBuser>mysite_app</DBuser>
            <DBpassword>pass</DBpassword>
        </Item>
        <Item>
            <id>50</id>
            <URL>https://m...content-available-to-author-only...e.com</URL>
            <Host>mysite.com</Host>
            <Folder>mysite</Folder>
            <Database>mysite_app</Database>
            <DBuser>mysite_app</DBuser>
            <DBpassword>pass</DBpassword>
        </Item>
        <Item>
            <id>100500</id>
            <URL>https://m...content-available-to-author-only...e.com</URL>
            <Host>mysite.com</Host>
            <Folder>mysite</Folder>
            <Database>mysite_app</Database>
            <DBuser>mysite_app</DBuser>
            <DBpassword>pass</DBpassword>
        </Item>
    </Items>
</Sites>
';
 
$doc = new DOMDocument();
$doc->loadXML($xml);
$items = $doc->getElementsByTagName('id');
echo 'Значение последнего ID: ', $items->item($items->length - 1)->nodeValue;

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