Complex sentence: The structure began as a fortress at a curve of the Moskva River three versts to the south-west of the Moscow Kremlin; it became an important part of the southern defensive belt of Moscow, which had already included a number of other monasteries.
Split into simpler sentences: The structure began as a fortress at a curve of the Moskva River three versts to the south-west of the Moscow Kremlin. It became an important part of the southern defensive belt of Moscow, which had already included a number of other monasteries.