A small harbour may have existed in the past at the base of Kastelli hill but the harbour of Chania as we know it was built by the Venetians over a period of 300 years, starting in 1320. It has two distinct basins: the West basin was mainly used for unloading goods that were stored in warehouses. The eastern basin was used to build and repair ships and was effectively the docklands. It was lined up by arsenals on one side and protected from storms by a long mole leading to the lighthouse.
The 'Arsenali' buildings were dry docks / shipbuilding / ship repair yards built along the eastern harbour between 1467 and 1599. There were 17 of them in a terrace and three more separate ones (the Docks of Moro, built in 1607) towards the eastern end of the harbour. The Arsenali were 50m long and 9m wide rectangular vaulted structures open at the sea side where a ship could be pulled out of the water and dragged into them in order to be worked on. Nine of them were demolished during the Turkish occupation when the docks were converted into military stores.
The Grand Arsenal was originally the end unit of the terrace of 17 vaulted buildings. It was built last, with thicker walls. During Turkish occupation the vault was replaced with a second floor. Later it became a Christian school, then a hospital. It also served as Chania city hall until 1941 when it was partly destroyed by a bombardment. It was extensively restored in 1997 and transformed into an impressive building that hosts various exhibitions and events. It also hosts the Center of Mediterranean Architecture and important Greek and International events related to architecture.
After the Venetians left Crete the harbour fell into disrepair. Because it is quite shallow and tended to silt up, most of the ship traffic moved to the well-protected waters of Souda Bay as well as to the deeper harbour of Heraklion.
Because Chania was quite poor and derelict in the 1960s there was very little interest in developing the area to tourism, leaving the harbour and its jumble of Venetian (and a few Turkish) buildings essentially untouched. In 1965 the part of Chania that is enclosed within the fortification walls was declared a protected historical monument. This controlled any developments and means that it now remains the most beautiful Venetian harbour in the Mediterranean.
The western basin is mainly lined with cafés and restaurants as well as a few shops and small hotels. In the summer there will also be a few excursion boats anchored in the basin.
The eastern basin is the marina and has many private pleasure boats as well as fishing boats anchored there. Along the harbour and between the Venetian arsenals there are many (mainly fish) tavernas which are well-frequented by the locals and foreigners alike.
Additionally don't miss the Nautical Museum located in the Firkas Fortress. One of the arsenals at the eastern end of the harbour (at the Moro Docks) is also part of the museum and houses the replica of a Minoan ship.