Вставте правильно were/was и если можно объясните как определить куда что ставить? There was a kremlin in the centre

1. There was a Kremlin in the centre of the town but in the eighteenth century its wall and towers were destroyed by a great fire. ( Were is for wall and towers).

2. In the eighteenth century the town began to grow because the road between St Petersburg and Moscow was built and the town stood near the road. ( was for the road).