Formerly known as Thyatira, and one of the Seven Churches of Asia, it's now a small market town in Manisa province. All that remains of Thyatira is a small set of ruins known as Tepemezarı, covering one city block.
Akhisar is not a tourist town, and you may be greeted with some incredulity by local children. However the people are friendly, and the architecture and horse-drawn carriages make it feel about a hundred years behind the times, and thus well worth a visit.
By busBuses run frequently from Izmir and Manisa. It's roughly a two hour bus ride from Izmir's Bornova bus station. From the Akhisar Bus station, Tepemezarı can be reached in a roughly ten-twenty minute walk. Walk south along the main highway for about a mile, and turn left onto Ismail Bahri Bey Cd.
By trainAkhisar can be reached from Izmir, Balikesir, or Bandirma by either of two daily trains between Izmir and Bandirma: the 6 Eylül or 17 Eylül Express. The station itself is seven blocks, or about 400 meters, from the ruins.
Akhisar is small enough that it's easy to walk around. You will also see plenty of horse-drawn carriages, however unlike in tourist areas, these are working animals, and it's unlikely you will be able to hire one.
Once you've seen Tepemezarı (which isn't that hard, as it's limited to a city block), walk around the town and take a look at the lovely architecture and horse-drawn carriages.
Walk around, and maybe hang out in one of the lovely parks that dot the city.
16 Sk. becomes a broad, pedestrian-only thoroughfare across from Tepemezarı, and has a number of restaurants (including a pizza place and a coffee shop) with a nice atmosphere.