Broad, spacious, empty, you can be specific about the size, and you can also compare it with other buildings, etc., and write about how many people it can hold, what kind of activities it can be used for, and so on.
Words to describe the square: wide, flat, tree-lined, Chinese lights. The crowd is surging.
Square is a wide area of the field, especially refers to the city's wide field. Is the city road hub, is the city people carry out political, economic, cultural and other social activities or transportation activities in the space, usually a large number of people, traffic distribution place. In the square or its surrounding is generally arranged with important buildings, often can focus on the performance of the city's artistic appearance and characteristics. Square in the city is not much, the area occupied by not much, but its status and role is very important, is one of the focus of urban planning and layout.