Acropolis - The high point or citadel of an ancient Greek city, like the Acropolis in Athens. It is generally a raised area above the rest of the city where the most important sacred and secular buildings are brought together. The buildings on the Athenian Acropolis were important for trade and worship.
Bitcoin is a digital currency (also called crypto-currency) that is not backed by any country's central bank or government. Bitcoins can be traded for goods or services with vendors who accept Bitcoins as payment.
A Bitcoin, however, is a virtual asset (not tangible), consisting of a numerical entry on a public ledger known as a Blockchain, and is owned by the possessor of a secret number, or private key.