When you get to Acropolis and see Parthenon, you realise the architecture, aesthetics and mathematics level of ancient Greek culture.
Europe since Rennaisance revealed the forgotten Greek classicism and later moved forward towards Enlightment Age, something that modern Greeks never came through (unfortunately) due to Ottoman occupation. Only revolutionary and liberal ideas passed to Greece since the French Revolution and combined with the Greek urban class abroad, gave birth to 1821 Independence War.
Greek merchants and intellectuals abroad founded Companies Filiki or Filomousos Etaireia (the name is met now in Kydathineon Street and many sponsors and donors assisted financially the Modern Greek state to stand. All Greek merchants were willing to return home and as soon as Athens was the new capital they started to buy land and build new houses. Moreover, Europeans already adored Greek classicism and imitated Greek forms, so that was a trend two centuries ago. Both trends met in Athens, soon afterwards its liberation from the Ottomans, and can be seen today in Plaka and also around Athens.
So Plaka is consisting of the ancient ruins, seen in churches and temples, neoclassical buildings and modern buildings. Plaka also includes parts of ancient walls, and Ottoman buildings. Everywhere you look, you will see something from the past.
Unlike other capital cities, Athens does not have a history of continuous expansion; it is one characterized by the glory of the golden age of the 5th century BC, followed by ups and downs near annihilation and then resurgence in the 19th century when it became the capital of modern Greece. All this vast history can be watched not only in Plaka’s timeline but everywhere in Athens. So even Plaka is the Old town of Athens, the rest of Athens is like smaller towns around the old own. Probably this is from where Athens> Athinais> many Settlements around temple of Athina, from Theseus times came.
For the moment there are no organised architectural walks of Athens, but soon there will be! Stay tuned!