counter = 2;
function trigger ()
{
	var myInterval = window.setInterval("imageswap()" ,3000);
}
function imageswap()
{
	var images = new Array(
		"building1",
		"building2",
		"building3",
		"building4",
		"building5",
		"building6",
		"building7",
		"building8"
		);
	var replaceme = document.images["replaceme"];
	replaceme.src = "images/building" + counter + ".jpg";
	counter++;
	if ( counter > 8 ) counter = 1;
}