Why was constantinople considered constantine i’s greatest achievement?

Constantinople (now Istanbul), establishing the Eastern Roman Empire, which would survive for more than a thousand years.

How  did spanish  power increaseunder charles  v and philip ii? in 1519,charles  v inherited a huge empire. he became king of  spain  and was also the heir to the hapsburg empire. during his 42-year reign, philip worked to expand  spanish  influence, strengthen the catholic church, and make his own power absolute. hope this !