Gloomy Dungeon

You nod and ask the gnome for the first riddle. He chuckles a raspy chuckle and starts:

 

"Firm an' stout we stand together,

on the same spot we're forever.

You visit us with ball and bat.

Do it daily, you won't get fat."

 

After a short pause he continues: "How many of us are there?" You think about this riddle. It must have something to do with the school; and it sounds sporty! What can you do during breaks near the school with a bat and a ball? And how many of those things are there?

 

Of course, the answer is ..