What's erected at regularly-visited Jumna by prince? (3,5)

I haven't cracked this one yet — but the brilliant team at Times for the Times have:

AT reversed [erected], J{u}M{n}A [regularly-visited], HAL (prince, at least according to Shakespeare). I’ve underlined most of the clue as I’m not sure what the definition is. The Taj Mahal was erected at Agra which stands on the River Jumna and it’s certainly regularly visited. I don’t think the prince is part of it.