The most expensive places in Monopoly are always the one right before start (so last). They are usually dark blue in color, but depending on the Monopoly edition, the names vary.
In a standard Monopoly game set, the most expensive properties are on the west side (with the GO square being on the top left) being Pacific Avenue ($300), North Carolina Avenue($300), Pennsylvania Avenue ($320), Park Place ($350) and Boardwalk ($400).
With a hotel, Pacific and No. Carolina Avenue charge $1100 to anyone who lands on them, Pennsylvania charges $1200, Park Place charges $1500 and Boardwalk charges $2000.
Mayfair is the most expensive property in British Monopoly.
The most expensive property on the UK Edition of Monopoly is Mayfair, costing £400
340.00
Boardwalk
boardwalk and parkplace are the set but boardwalk is the most expensive.
340.00
Mayfair
In Monopoly, the property that follows Mayfair in terms of value is Park Lane. Park Lane is the most expensive property on the board, and it is situated adjacent to Mayfair. Together, they form the most lucrative color set, the dark blue properties, which yield high rents when developed with houses or hotels.
Mayfair
In the game of Monopoly, Boardwalk is the most expensive property, costing $400. It is part of the Dark Blue color set along with Park Place. When developed with houses or a hotel, it can yield significant rent, making it a valuable asset in the game.
Boardwalk.
Illoinos Avenue