Why do some tiles look like a construction site?

Some buildings and items are spread across multiple adjacent tiles, and tapping one tile will not complete them. The item or building will only appear in your Town after you build all the tiles that make up the entire building or item.

In the meantime, tiles belonging to unfinished buildings or items will look under construction, signaling that you still need to build the rest.

For example, if a building is spread across 3 adjacent tiles, the first and second tiles will appear under construction. Once you build the third and final tile, the entire building will appear in all its glory.