Complex sentence: At the time that the prince was planning to buy the land on the outskirts of Vienna for his Belvedere project, the area was completely undeveloped¾an ideal place to construct a landscaped garden and summer palace.
Split into simpler sentences: At the time that the prince was planning to buy the land on the outskirts of Vienna for his Belvedere project. The area was completely undeveloped, which made it an ideal place to construct a landscaped garden and summer palace.