Complex sentence: It is one of the few cities in the European Union to have such a skyline and because of it Germans sometimes refer to Frankfurt as "Mainhattan", a portmanteau of the local Main River and Manhattan.
Split into simpler sentences: It is one of the few cities in the European Union to have such a skyline. Because of the city's skyline, Germans sometimes refer to Frankfurt as "Mainhattan", a portmanteau of the local Main River and Manhattan.