Istanbul
Hagia Sophia
1,500 years after being built, Istanbul's architecture still hasn't produced a building to rival the beauty of the Hagia Sophia. Dating all the way back to the Roman Empire, the building has served the city as an Orthodox Church, a secular museum, and once again as a mosque.
Alongside the huge dome, the highly decorative interior will leave any visitor awestruck that hands are capable of creating something so impressive. Keep an eye out for early Christian motifs inside the epitome of Byzantine Architecture that is still just as powerful today.