Complex sentence: The highway GR-1 aka E75 surrounds the northern and eastern part of the mountain along with the Cephissus river, while the Attiki Odos freeway (GR-6) runs to its south.
Split into simpler sentences: The highway GR-1 aka E75 surrounds the northern and eastern part of the mountain along with the Cephissus river. The Attiki Odos freeway (GR-6) runs to its south.