Country retreats of Roman Emporers

I read an interesting article in "Smithsonian" about the country villa retreats of the Roman Emperors. The Villa Magna of Marcus Aurelius is located in the Valle del Secco in Lazio, south of the town of Anagni looked very interesting. I definitely want to see it. Another is Emperor Hadrian's Villa Adriana by the city of Tivoli about 30 km from Rome.Villa Adriana (Tivoli) - UNESCO World Heritage Centre.