Khor Virap Monastery is located just a few hundred meters from the Turkish border and very close to Mt. Ararat (Armenia's sacred mountain where Noah's Ark is supposed to have landed). St. Gregory was imprisoned here in the 3rd-4th century for being a Christian. When he survived a dark cell for 12 years and was able to cure the king's illness, the king converted to Christianity and Armenia became the first Christian nation in 301.
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.
Located outside of Yerevan, Gerhard Monastery is believed to have been a monastery since the 4th century when early Christians lived in the caves and developed cave churches. The church pictured, Surp Astvatsatsin, dates from the early 13th century.