A recent study of housing affordability in North America put Boston in the top 10 most expensive cities. The city came in No. 7 in the analysis from Point 2 Homes, which measured cities’ median multiple — the median home sale price divided by the median annual family income. With a median home sale price of $610,000 and median family income of $61,176, it takes owners in Boston 10 years to pay off their homes. Vancouver topped the list of most expensive cities, and the most expensive city on the list is Manhattan, where it takes 15.6 years to pay off a home.

Elsewhere in the metro area this week:

• Construction has started on Cambridge’s Mass + Main, which will add three buildings and 306 apartments to the city’s skyline. One of the buildings will be 19 stories, making it one of Cambridge’s tallest, according to Curbed. Construction is slated to wrap up in 2019.
• You may recall that a condo sale in Millennium Tower was last week’s biggest sale, and this week is no different. A three-bedroom, four-and-a-half bath unit sold for $6.7 this week, according to the Boston Globe. The swanky glass-walled, 3,172-square-foot home comes with two valet parking spaces.
• Apparently some aren’t satisfied with the name of the West End neighborhood: Rapid7 recently relocated to the area, but in a press release, referred to it as Uptown. Do you think the new nickname will stick?
• A 4.7-mile extension to the Green Line may be underway before the year ends, according to the Globe. The project, which will extend the line through Somerville into Medford and include seven new stations, is scheduled to be wrapped up in 2021.