Cambridge-based developer Carpenter & Company will join executives from Four Seasons to break ground on what will become Boston’s tallest building, the Four Seasons Hotel & Private Residences One Dalton Street, Wednesday night at 6 p.m. Mayor Marty Walsh is expected to attend as the guest of honor.

The completed tower will rise 699 feet (61 stories) above from the heart of the Christian Science Plaza, trumping the height of the highly anticipated Millennium Tower (685 ft.) under construction in Downtown Crossing. The Four Seasons is expected to house 211 hotel rooms and 180 condo units.

Related: Millennium Tower construction photos

While the Four Seasons won’t stand as tall as the Prudential or Hancock towers, the new residential skyscraper (designed by Harry Cobb, of architecture firm Pei Cobb Freed, and Gary Johnson, of Cambridge Seven Associates) is nonetheless a significant development. A 699-foot-tall building is “phenomenal height by both contemporary and historical standards,” Curbed‘s Tom Acitelli writes, since “it’s damned near impossible to build anything taller than 200 feet in Boston these days…”

The new Four Seasons is the tallest new project to break ground in Boston since the 790-foot-tall John Hancock Tower, which was completed in 1976.

Rendering via Cambridge Seven Associate/Pei Cobb Freed.