Ejmiatsin is the Armenian equivalent to Vatican city. It's not as grand and pompous, of course, but you can definitely feel a difference from the other religious sites: here priests are everywhere, looking busy and important. There's nothing of the charm of the remote monasteries set in stunning natural locations. The city is ugly. I didn't find Ejmiatsin appealing at all.
Ejmiatsin became the spiritual center of Armenia in the early 4th century. The cathedral still has a 5th century wall. But most of the building is from the 17th century. The city has 3 other main churches: St Hripsime (Hripsime was one of the refugee nuns from Rome in the late 3rd century who was persecuted by King Trdat III -the king himself allegedly tried to rape her), St Gayane (the abbess of the fleeing nuns) and St Shokagat (a companion of Gayane and Hripsime). All of these churches were rebuilt during the 17th century.