The grid plan, grid street plan or gridiron plan is a type of city

City

A city is a relatively large and permanent settlement. Although there is no agreement on how a city is distinguished from a town within general English language meanings, many cities have a particular administrative, legal, or historical status based on local law.For example, in the U.S...

 plan in which street

Street

A street is a paved public thoroughfare in a built environment. It is a public parcel of land adjoining buildings in an urban context, on which people may freely assemble, interact, and move about. A street can be as simple as a level patch of dirt, but is more often paved with a hard, durable...

s run at right angles to each other, forming a grid. In the context of the culture of Ancient Greece

Ancient Greece

Ancient Greece is a civilization belonging to a period of Greek history that lasted from the Archaic period of the 8th to 6th centuries BC to the end of antiquity. Immediately following this period was the beginning of the Early Middle Ages and the Byzantine era. Included in Ancient Greece is the...

, the grid plan is called Hippodamian plan.
The grid plan dates from antiquity and originated in multiple cultures; some of the earliest planned cities were built using grid plans.

By 2600 BC, Mohenjo-daro

Mohenjo-daro

Mohenjo-daro is an archeological site situated in what is now the province of Sindh, Pakistan. Built around 2600 BC, it was one of the largest settlements of the ancient Indus Valley Civilization, and one of the world's earliest major urban settlements, existing at the same time as the...

 and Harappa

Harappa

Harappa is an archaeological site in Punjab, northeast Pakistan, about west of Sahiwal. The site takes its name from a modern village located near the former course of the Ravi River. The current village of Harappa is from the ancient site. Although modern Harappa has a train station left from...

, major cities of the Indus Valley Civilization

Indus Valley Civilization

The Indus Valley Civilization was a Bronze Age civilization that was located in the northwestern region of the Indian subcontinent, consisting of what is now mainly modern-day Pakistan and northwest India...

 (present day Pakistan), were built with blocks divided by a grid of straight streets, running north-south and east-west.