Although long walls were built at several locations in ancient Greece (Corinth and Megara being two of the best known examples) the Long Walls (Greek: Μακρὰ Τείχη) generally refers to the walls built in several phases and connecting Athens to its ports at Piraeus and Phalerum, providing a secure connection to the sea even during times of siege. These walls were of about 6 km in length, were constructed in the mid 5th century BC, destroyed by the Spartans in 403 BC after Athens' defeat in the Peloponnesian War and rebuilt again with Persian support during the Corinthian War. They were a key element of Athenian strategy, since they provided the city with a constant link to the sea and prevented it from being besieged by land alone.