So, anytime we are talking about Native American tribes, the first question to ask is which region? The tribes were as varied as their environments, and some tribes did in fact construct large urban centers like those seen in Mesoamerica and South America. The easiest example of this would be the ancestral Puebloans, who lived in Mesa Verde (link: https://www.nps.gov/meve/learn/historyculture/cliff_dwellings_home.htm) or Chaco Canyon (link: https://www.nps.gov/chcu/planyourvisit/pueblo-bonito.htm).
Depending on what you consider to be ‘architecture’ or ‘monuments’, you could also look to the Pacific Northwest tribes such as the Haida, Tlingit, Tsmishian, etc., where you get the classic images of Native American artwork, the totem poles (link with some nice pics: http://donsmaps.com/pacificnorthwest.html).
In order to construct cities and monumental architecture, a society needs to have a sedentary food source. In most cases, this meant farming. Often when we see monumental architecture, it reflects the type of subsistence strategies practiced by the society in question. The Meso- and South American cultures and the ancestral Puebloans relied heavily on corn cultivation. The Pacific Northwest tribes were an exception to the rule about agriculture, and were able to support a sedentary lifestyle through hunting and gathering due to the richness of their natural environment. If we are talking about the tribes in the Great Plains, such as the Sioux, Crow, Cheyenne, Cherokee, etc., these tribes were largely dependent on a mobile subsistence strategy following the introduction of the horse. They would follow the herds, establishing seasonal camps throughout the year, and move between them. Needing to move every few months largely precludes any large-scale construction.
These are only a couple of examples, and are by no means comprehensive of the entirety of the extremely diverse Native American cultures.
Edit: Corrected poorly made generalizations and added qualifiers
There's always room for discussion but perhaps the section Technology and Civilization in the Americas from our FAQ will answer your inquiry.
You are most likely asking this question because you don't see any outward evidence of monumental construction in the US and Canada. In reality, natives of North America practiced monumental construction on the same/similar scale to natives in South and Central America. Poverty Point in Louisiana is a World Heritage site and dates to the Archaic Period, ~2000 BCE, and it's not even the earliest example of mound building in NA. Huge effigy mounds in the shape of animals and creatures are found across the US and especially in Wisconsin and Ohio. The Great Serpent Mound in Ohio is almost a quarter mile long. Cahokia was a Mississippian native community with several large mounds (Monk's Mound is around 100' high and covers 13 acres) and an artificially flattened plaza (50 acres). It reached it's peak around 1200 CE and the highest estimates of it's population are around 40,000 inhabitants.
Misconceptions around Native North Americans and their perceived lack of monuments are very common and answers like /u/CuddlyWingman's are misinformed. Natives in NA have a tradition of mound building of at least 4,000 years and is in no way limited to the SW or NW because the earliest example we have found is Watson Brake in Louisiana. The popular depiction of the native as hunting a buffalo on a horse (introduced by the Spanish) has dominated the perspective, while many tribes practiced agriculture and built very impressive monuments, but that side of history is less talked about and not often in the public eye.
Sources:
John Blitz "Moundville"
George Milner "The Moundbuilders"
Richard Townsent ed. "Hero, Hawk, and Open Hand"