Heads up, deal hunters! There's a sweet fare popping up for flights to Porto, Portugal (OPO) for under $700 roundtrip on United and its Star Alliance buddies like Air Canada, Austrian, Lufthansa, and Swiss Air. While it's regular economy (meaning you'll likely pay extra for checked bags and seat selection), this is a fantastic price for getting yourself to a beautiful European city. Why should you care? Well, Porto is gorgeous, the port wine is amazing, and deals like this don't stick around forever. If you've been dreaming of exploring Portugal without breaking the bank, now might be the time to pounce. Consider using a travel rewards card that earns bonus points on airfare to maximize your return! Just remember to factor in those extra fees for things like baggage when comparing it to other potential options.