Nostalgia Properties, a subsidiary of the Allston-based real estate management firm The Hamilton Company, bought 316 units of housing in Arlington and Cambridge from Brattle Realty last month for $41 million.

According to the company’s website, the properties include 333, 385 and 898 Mass. Ave.; 9 and 15 Chester Street; 11, 15 and 19 Dudley Street; 50 and 54 Grove Street; 11 Allen Street and eight buildings on Brattle Drive. The properties include studios, one-bedroom, two-bedroom and three-bedroom apartments and offices.

“It’s not often that a portfolio of quality real estate is put up for sale. Especially in today’s day and age, there are not many multi-family properties up for sale,” Hamilton Co. President Carl Valeri said.

Many of the units have not seen any increases in rent prices for about six years, so a cost of living increase could happen in 2011, he said.

Valeri, an Arlington resident of nearly 30 years, said he believes Arlington is a community that people like moving to because of its strong middle class demographic, its proximity to Boston, its town management and great restaurants.

The purchase is significantly smaller than the company’s 2009 acquisition of Dexter Park in Brookline for $129 million but larger than most of Hamilton’s investments, which Valeri said tend to hover between $10 and $15 million. The Brattle Realty arrangement was the company’s first asset in Arlington and Valeri said he looks forward to buying more of the town’s real estate in the future.

In addition to the properties’ attractiveness from a business standpoint, Valeri said he was interested in the area because of his family’s Arlington roots. His father, Robert Valeri, was childhood friends with Brattle’s former owner, Eldridge “Bud” Johnson. As an adult, Robert Valeri did repair work on the properties through his own company, Valeri Construction.

“My father’s company did a lot of work for his company, Brattle Realty, and I worked on the properties as a teenager,” he said. The Valeri family built several homes in Arlington.

Hamilton Co. owns nearly 5,000 apartments in eastern Massachusetts.