Byplaces refer to small, out-of-the-way places, but there are certain antonyms that can be used to describe opposite types of places. One such antonym is "mainstream," which refers to popular, well-known areas. Another antonym is "highway," which describes busy, well-traveled roads. Additionally, "metropolis" is an antonym for byplaces, referring to large, urban areas with lots of activity and people. Finally, "famous landmarks" could also be an antonym, as they are popular and well-known places that attract lots of tourists. Overall, antonyms for byplaces describe popular, busy, or larger areas that are well-traveled and well-known.