This is the famous Venetian castle in Heraklion,Crete named "Koules". It is located near the port of the city in a place called "small port" where the little boats are parked. It considers to be the landmark of this beautiful city. If you are in town for holidays it's easy to get there since the bus station is 2 minutes walk away, so all the busses are passing. You can also take a walk to the beautiful and picturesque little streets around the castle that guide you downtown for shopping or sightseeing! Another option is to walk from the castle to the lighthouse which is around 1km away and the pavement is exactly next to the sea! Have a nice time and safe travels!