Echmiadzin, outside of Yerevan, is the seat of the Patriarch (Catholicos) of the Armenian church. Many Armenians call it their Vatican. All Armenian churches in the world use holy oil that originated from this church. ..The church has an impressive treasury where the remains of apostles and saints are held in silver arm-shaped reliquaries (looks a bit like armor). It also holds remains of Noah's ark (supposedly) and the Holy Cross.
Read more about Armenia's sights and churches.