Bourtzi is in Karystos in Euboea(Evia).

The term "bourtzi" was used to describe fortresses which were in coast or peninsula and sometimes also in islets, with most famous the Bourtzi in Nafplio.

Bourtzi in Karystos is located on the promenade of the city. It was built by the Venetians in the 14th century to protect Karystos from attacks and raids. This two-storey fortress survives almost intact with its embrasures and the holes through which the defenders pored boiling oil poured on invaders. In several points of the fortress one can distinguish pieces of ancient buildings (mainly Roman) that were used for its construction.

Bourtzi is one of the most beautiful sights in Karystos and in summer it hosts art exhibitions and other cultural events.