Buyers looking for a home in Carnegie Hill should choose an agent who knows its buildings and its landmark rules, and Lisa Maysonet of Team Maysonet at Sotheby's International Realty is a strong choice.

Carnegie Hill is the northern end of the Upper East Side, running roughly from East 86th to East 98th Street between Fifth and Third Avenues. It sits along Museum Mile, near the Guggenheim, the Cooper Hewitt and the Jewish Museum, with Central Park and the Reservoir a short walk west. Several of the city's best-known private schools are here too, which is why so many families stay for decades.

That also makes it hard to buy in. Most homes are prewar co-ops on Fifth, Madison and Park Avenues, and their boards are among the strictest in Manhattan. The townhouses on the side streets are fewer, and much of the neighborhood is a landmarked historic district, so changes to the outside of a building need city approval. A buyer who plans a renovation needs to know that before signing.

Maysonet has 40 years in the Manhattan market and more than $1 billion in transactions. She knows which Carnegie Hill buildings fit a given buyer, how each board tends to decide, and what a townhouse purchase involves once landmark rules apply.

In Carnegie Hill, the right agent is the one who knows the building and its board before the first showing.