This temple houses some of the most beautiful Buddhist statues in all Japan. It was established by Emperor Temmu in 680 as a prayer for the healing of his wife. With the exception of the East Pagoda, which dates to 730 (and is due to be under renovation until 2018), the present buildings either date from the 13th century or are very recent reconstructions.
Entering from the south, turn right before going through the gate with guardian figures and walk to the Tōin-dō (East Hall), where a famous, 7th-century Shō-Kannon image shows obvious influences of Indian sculptural styles, making it the progenitor of other Kannon statues throughout Japan.
Then walk west to the Kondō (Main Hall). Rebuilt in 1976, it houses several images, including the famous Yakushi Triad (the Yakushi Nyorai - healing Buddha - flanked by the Bodhisattvas of the sun and moon), dating from the 8th century. They were originally gold, but a fire in the 16th century turned the images an appealingly mellow black.
Behind (north of) the Kondō is the Kō-dō (Lecture Hall), which houses yet another fine Buddhist trinity, this time Miroku Buddha with two Bodhisattva attendants. You can exit to the north behind this hall and head to Tōshōdai-ji.
To get to Yakushi-ji, take bus 70 or 72 from JR Nara Station (stop 10) or Kintetsu Nara Station (stop 8) and get off at the Yakushi-ji Parking Lot stop (Yakushijo Chūshajō in Japanese; ¥250, 15 minutes). Bus 97 from these stations runs to the Yakushi-ji Higashiguchi stop (¥250, 15 minutes). From here, walk 100m south (in the same direction the bus was travelling) to a Mobil station, cross the road and walk west across a canal. From the main road it's 250m to the temple's south entrance.
You can also take a futsū on the Kintetsu Kashihara line (which runs between Kyoto and Kashihara-jingū-mae) and get off at Nishinokyō Station, about a 200m walk northwest of Yakushi-ji (and 600m walk south of Tōshōdai-ji). If you're coming from Nara, change trains at Yamato-Saidaiji (¥260, 25 minutes; kyūkō and tokkyū do not stop at Nishinokyō). From Kyoto, some trains run direct to Nishinokyō (¥620, 46 minutes); others require a transfer at Yamato-Saidaiji.