Sarajevo was under Ottoman rule, once upon a time. The Beg, a title for one of the Sultan's right-hand men, was ordered to build a mosque in honor of the Sultan in Sarajevo. Word apparently reached the Sultan that the Beg was in fact building two mosques, the second one in honor of himself, and it was bigger and grander. So the Sultan ordered the Beg to switch mosques with him. But it turned out that the rumor was false, so the Sultan ended up with the smaller, more humble mosque. Or so the legend goes. This is the smaller one, I don't have a good picture of the big one.