Today, it is not a port city anymore but after excavated, it is one of the most beautiful ancient cities of modern day Turkey, so Ephesus is located in Turkey. Exactly in Izmir province, a few kilometers out of Selcuk town.
How can you go to Ephesus? First you should find your way to Selcuk. If you are in Istanbul, you can either take a flight to Izmit ADB airport or take an overnight bus to Selcuk. If you are in Pamukkale, you can take a bus or train. If you are in Cappadocia, an overnight bus or a flight to Izmir airport will be the best choices. If you are already in Izmir center, I highly recommend you to book a tour but you can also take public transportation to Selcuk if you go to Otogar, main bus station. If you take a flight, you can book a transfer to Selcuk or if you are a solo traveler, you can take Havas busses. The train and overnight bus comes directly to Selcuk town center.
Once you make to Selcuk, it is pretty easy. You can either take a taxi or public transportation called Dolmus to the south gate. Also if you are willing to walk you can walk to the south gate as well.
But if you really want to use your time and energy wisely, you should start from the north gate which is about 7 kms to the town. You can take a taxi to the north gate.
But what I really recommend is to join to a tour group. Why should you book an Ephesus Tour? Because there are more than one place to visit in this area and they are relatively scattered. Tour groups take you to Virgin Marry's House, Artemis Temple, Isabey Mosque as well as Ephesus ruins. If you visit them by yourself you have to take taxi and it will be expensive. You cannot walk to Virgin Marry's House which is a very important point to visit once you are in this area. Also tour groups are always with a professional guide and this area is so rich in culture and history, visiting with a guide will make your experience deeper and richer. Tours take you to lunch and drive you everywhere, take care of parking fees etc. It really worths to pay for a tour. You will not feel like dragged after the group since the guides in this area are very experienced and professional also schedule is not tight so you will not be in rush. Another pro of booking of a tour is once you book it, they will take care of transfers and all the other schedule. You won't have to worry about missing your bus or flight or finding your hotel for that night. Once you are in, they will offer you other services and it will make your trip really easier.