From the Incheon Airport, there are no direct buses to Gongju. You'll have to take a bus to Seoul's Gangnam express bus terminal and transfer to a bus there, or take a bus to Daejeon Bus Terminal and catch a bus from there. The way via Daejeon requires less walking, but will add about 1 1/2 to 2 hours to your trip.
From Seoul's Express Bus Terminal, you can get a bus to Gongju (which terminates at Buyeo). Express buses run every 30 to 40 minutes and take under 2 hours of travel time. The intercity and express bus terminals are next to each other north of the river. Express buses from Daejeon go to Gongju every 5 to 10 minutes and take under an hour. From the East Daejeon Terminal, there are 22 departures daily 7am to 9pm and the bus takes 70 minutes. From the West Daejeon Terminal, buses run about every 5 minutes, daily from 6:30am to 10:30pm, and take an hour. If you take a bus from Daejeon, they'll most likely take you to the city center.
There are no direct trains that come into Gongju; you'll have to take a train to Daejeon or a Mugunghwa train to Jochiwon and transfer to a bus.
The city bus station is in the middle of town. Here you can catch local buses to most places of interest. You can also flag down a taxi from any street. Neither bus nor taxi drivers speak English, but they will help you get where you want to go, regardless.
The tourist info center, 65-3 Geumseong-dong, Gongju-si (tel. 041/856-7700), is located at the parking lot below the entrance to Gongsanseong.
The city offers a free bus tour of the city's most important places every Sunday from April to October. The all-day tour (it lasts just under 8 hr.) starts at 10am from the parking lot of the Gongsang fortress. It stops at King Muryeong's Tomb, the city's national museum, and the folk museum. Call the Gongju Tourist Info Center (tel. 041/856-7700) to make the required reservations. Admission fees aren't included in the tour.
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