Argostoli, which became the capital of Cephalonia in the 18th century, is a nice, beautiful town of about 10 000 inhabitants, where you can find all the administrative offices and the main part of the island's cultural life.
In Argostoli you can find the Prefecture of Cephalonia and Ithaca, the educational administration, the offices of the Ionian region, the Town Hall, a dozen of schools, the cinema-theatre Kephalos, the main police station, the port authorities, the Tourist Office, sports grounds (a stadium, the municipal swimming pool, tennis courts, basketball courts...), sports associations (sailing, hiking, cycling...), cultural associations, the folklore and archaeological museum, the Kosmetatos foundation, the Korgialenios library and archive (the second biggest in Greece, after the National Library in Athens, founded also by a Cephalonian!), lots of boutiques, some supermarkets, an important industrial zone, the central bus station KTEL, etc. In other words, you won't have the chance to get bored.
The commercial road of Lithostroto (meaning paved road) has got both tourist shops and clothes shops, and will lead you to Vallianos main square and Rizospaston Street (meaning the street of the Radicals), which is often called Palm street. There are numerous café-bars and restaurants around the square and along Rizospaaton Street which are also the centre of the island's night life, especially in wintertime.
On the seafront, invaded by sailing boats and yachts in the summer, you will be able to find some taverns, as well as a permanent fruit and vegetable market, which is closed only on Sundays. Early in the morning, the fishing boats come to sell fresh fish, which attract seagulls as well as a sea turtle, which stars in almost every tourist's camera. If you go on with your walk, you will reach De Bosset's bridge, on which you will see many people using their fishing lines to catch fish. This bridge connects Argostoli with the opposite side which is called Drapano. Once upon a time, vehicles used to pass by the bridge but now it is prohibited so you can have a walk on the bridge without anything annoying you.
Other places to visit around Argostoli : Saints Theodoroi lighthouse, where couples meet and from which you can admire the sunset, Koutavos lagoon, a protected zone as it is frequented by numerous migratory birds, and finally the monument dedicated to the dead soldiers of the Italian Acqui division (WW II), on the hill above the town.