In the ninth year of Zedekiah’s reign, Nebuchadnezzar came to Jerusalem. From the massive attack and the personal presence it becomes evident that Nebuchadnezzar is very much offended by the rebellion of Zedekiah. The start of the siege happened in winter, and the winter was not the preferable season to wage war. This is also an indicator of how much it meant to Nebuchadnezzar to deal with Zedekiah and Jerusalem.
Carefully translated, 2 Kings 25:1 sounds like this: Nebuchadnezzar laid siege to Jerusalem. And they built a siege rampart around the city.
This shows that Nebuchadnezzar instructed his soldiers to build the ramparts; his head office was in Riblah, and perhaps he stayed there during the construction of the ramparts.
1 La neuvième année du règne de Sédécias, le dixième jour du dixième mois, Nebucadnetsar, roi de Babylone, vint avec toute son armée contre Jérusalem; il campa devant elle, et éleva des retranchements tout autour.