The Masjid Al Aqsa is the second house of prayer established on earth:
Abu Dharr reported:
I said: “Messenger of Allah, which mosque was set up first on the earth?” He said: “Al-Masjid al-Haram (the sacred mosque, in Makkah)”. I (again) said: “Then which next?” He said: “It was the Masjid Aqsa.” I (again) said: “How long the space of time (between their setting up)?” He (the Holy Prophet) said: “It was forty years. And whenever the time comes for prayer, pray there, for that is a mosque; (for you).” (Sahih Muslim ,Book #004, Hadith #1056)