Based on the function:
* House: If you're talking about a place to live, a house is the opposite of a tent.
* Building: If you're talking about a more permanent structure, a building is the opposite of a tent.
* Shelter: While "shelter" itself isn't an antonym, "no shelter" could be used in some contexts.
Based on the material:
* Solid: This is an antonym if you're focusing on the temporary nature of a tent.
* Permanent: This is another antonym if you're focusing on the temporary nature of a tent.
Based on the size:
* Palace: This is an antonym if you're focusing on the smallness of a tent.
Ultimately, the best antonym depends on the specific meaning of "tent" in your sentence.