Runs fine in the playground

I guess the challenge meant it when it said you didn't have to name the return values. So you need to lose the lat lon:

func getTowerCoordinates(location: String) -> (lat: Double, lon: Double) {

Also, if a function returns two values in a tuple, you don't redeclare those values in the function. So you need to delete these two lines:

    let lat: Double
    let lon: Double

But the most important part is you need a return statement for each case (and the default):

func getTowerCoordinates(location: String) -> (Double, Double) {

    switch location {
    case "Eiffel Tower":
        return ( 48.8582, 2.2945)
    case "Great Pyramid":
        return ( 29.9792, 31.1344)
    case "Sydney Opera House":
        return ( 33.8587, 151.2140)
    default:
        return ( 0, 0)
    }

}

The general rule is one return statement for each possible path through your code. Here there are 4 possible paths, and each needs its own return statement.

Yes, it runs fine in a playground. It's not that you can't do it that way. Ben was asking, or so I thought, why it wouldn't work in the challenge. And, as it happens, if you don't name the return values and you leave out the let statements it works! Admittedly the editor is a bit picky, but if you want to complete the challenge you have to make some "compromises".

Good point. I didn't try all the possible variations before responding.