NE Attica, the area between Pentelikon Mt. and Southern Evoikos Gulf (Fig. 1), represents the northwestern prolongation of Attic-Cycladic Crystalline Complex (ACCC). It consists of metamorphic rocks equivalent to those of Southern Attica, Southern Evia and the Cyclades. A small amount of research has been carried out in Attica and even less in NE Attica. Most researchers accept the geotectonic scheme given by Marinos & Petrascheck (1956) for the area of Lavrion (Southern Attica), which comprises a relative autochthonous tectonic unit (Lower Unit) and an overlying allochthonous Phyllitic Nappe (Upper Unit). Recent publications (e.g. Katsikatsos et al. 1986, Photiades & Carras 2001, Skarpelis et al. 2008, Liati et al. 2009, Baziotis et al. 2009, Krohe et al. 2010, Spanos et al. 2010, Xypolias et al. 2010, Baziotis & Mposkos 2011, Liati et al. 2013, Baziotis et al. 2019) correlate the Lower Unit with the Basal Unit and the Upper Unit with the Cycladic Blueschist Unit (CBU). The aim of this field-guide is to: i) propose a new refined lithostratigraphy of NE Attica, ii) present a geological map in scale 1:25.000, iii) present new structural and petrographical data for the structural evolution of this part of the ACCC and iv) propose two one-day field trips (from Pentelikon Mt. up to the coastal zone of Southern Evoikos Gulf) that will shed light both to the NE Attica lithostratigraphy and macrostructure of the Lower and Upper units as well as the main structures formed mainly during the retrograde path. The stops of the two, one-day, excursions and the geological map in scale 1:25.000, are also given online, as .kmz (Field-trip.kmz) and .pdf (Geological Map.pdf) files respectively.