ruins
n. C / U B1 Intermediate US //ˈɹuənz// UK //ɹˈuːɪnz// ru·ins
n. the broken parts of a building or city that was destroyed a long time ago. You often visit these places to learn about history.
n. the remains of a building, city, or structure that has been destroyed or has decayed over time. Often used in the plural to refer to an archaeological site.
We spent the afternoon exploring the Roman ruins.
The ancient ruins of the castle sit on top of a hill overlooking the modern village.
Archaeologists spent decades excavating the ruins to understand how the civilization managed its water supply during periods of extreme drought.
Usage
Usually plural when referring to physical remains of buildings; singular 'ruin' often refers to the state of being destroyed.