There is a lack of landmarks for the 75 hiking paths on this mountain, but there is a guide called Footpaths of Mt. Parnitha and map by Road Editions that outline these hikes well.
Right outside Agios Konstantinos (Kamarizas) on the way to the church of Agia Triada is Chaos, a unique geological phenomenon in Attica. It is a large round gulch with a perimeter of roughly 500 meters and a depth of 70 meters.
While often plagued by forest fires in summer, the elevation of upto 1,100 meters on its eastern slopes may reveal several species of birds. These include Hooded Cirl Buntings, Crows, Jays, Red-backed Shrikes, Sparrow Hawks, Western Rock Nuthatches.
Also noteworthy is Lycabettus or Likavitos Hill in Athens almost in the centre of town. In addition to great views of the port of Piraeus and all of Athens, a rocky area on top attracts many rock-loving birds. You might see a Bunting, Chaffinch, Great Tit, Sardinian Warbler and many more.
The closest and largest birdwatching locale in the city is the mountain of Hymettus or Imittos in Greek. It is about 20 km long and 1026 km high, offering a great location to hike and spot birds.
Mount Hymettus is famous for its thyme-scented honey. It is covered with beautiful pine forest, impressive caves, historic monasteries and many marked footpaths, just a five or ten minute drive from downtown Athens.
The most well-known cave on Hymettus is Koutouki cave in Peania which hosts guided tours. Sadly, too much lighting and human presence has degraded the natural characteristics of the cave.
On the southeast side of Hymettus near the area of Vari, this open precipice impresses you with its mouth and runs 20 meters deep. Speleologists practice climbing up and down over here.
This is the highest peak near Athens towering at 1,400 meters. Past the cable car station at the upper elevations in the mornings and evenings is bound to reveal the most birds. You could spot a Coal Tit, Firecrest, Flycatcher, Great Tit, Jay, Magpie, Sardinian Warbler, Western Rock Nuthatch and more.