Certain urban projects reflect arcological principles. Pedestrian connection systems often provide a wide range of goods and services in a single structure. Some examples include the +15 system in downtown Calgary:
or the Minneapolis Skyway System:
They include supermarkets, malls and entertainment complexes. The +15 is the world's most extensive skywalk, 16 km (10 miles). Minneapolis has the longest single path, eight miles (13 km).
The largest arcology project under current development is Masdar City near Abu Dhabi, in the United Arab Emirates. It is projected to house between 45,000 and 50,000 inhabitants on 6 square kilometers, and to have a sustainable, zero-carbon, zero waste ecology.