Daphni, Hosios Loukas and Nea Moni of Chios by Nan
The Byzantine monasteries of Daphni, Hosious Louas and Nea Moni were built in the 11th century, in what amounted to the peak of Roman power and also the beginning of the ultimate demise. Around the turn of the millennia, the Romans had pushed the Arabs out of the Eastern Anatolian border regions and recaptured parts of Armenia and Syria, protecting their Anatolian heartlands against the incessant Arab raids of previous centuries. On the Balkans, Emperor Basil II, aptly nicknamed the Bulgar Slayer, had subdued the Bulgarian Empire in a decades spanning war. When he died in 1025 CE, the Empire was as powerful and large as it hadn't been since Justinian.
A mere 50 years after the death of Basil II, though, in 1071 CE the historic battle of Manzikert resulted in the Romans losing control of most of of their Anatolian heartlands to the Turks. The Romans would only continue to control the coastal towns. Nowadays, most historians consider Manzikert the beginning of the end of the Roman (Byzantine) Empire.
Daphni was built after Manzikert in 1080. I wonder how the Romans of the period perceived this epic event marking a turning point in history. Probably, it didn't occur to them that they had just witnessed the beginning of the end. If you are interested, I can recommend the Byzantine History Podcast.
In how far it impacted their architecture is hard to tell. It would be interesting to compare all three inscribed sites and see the evolution of architecture and style in the 11th cencutry. It's probably too easy to say they must have found religion. Truth be told, the Eastern Roman Empire had always held religion in high esteem to a degree unfathomable today.
Daphni itself is a small monastery. Due to an earthquake the mosaics and icons are damaged. Frankly, I have seen better, e.g. in Istanbul. In addition, being situated directly on a major road out of Athens the mood is not really tranquil.
Getting There
I tried to get to Hosios Loukas using public transport, but I really couldn't make it work. I think the easiest option is to take a return cab from Delphi. Daphni, meanwhile, is trivial. You drive right past it if you are driving from Athens to Corinth and the Peloponnese.
By public transport, you get off the metro at Agia Marina. From there catch a bus (811, 866, 876). Note: Google maps will propose dropping you off right in front of the monastery. Tiny issue: There is the aforementioned highway in between you and the monastery, so you will have to backtrack one bus stop for the traffic light; I had to. To save yourself the walk, get off one stop earlier than proposed by google.
The monastery is free but opening times are limited, so check in advance. At the time of writing, it's Wed-Sun 8:00-15:30. They make you ring the bell to enter.