Skyscrapers are not ordinary buildings but rather “pyramids of our civilization, permanent monuments of our existence,” writes The New York Times. Their construction can reshape the skylines of major cities across the globe in dramatic ways. Take a mini-tour through time of the rise of one East Coast city and one West Coast city.

The Development of Downtown Boston

Known by its address, Boston Properties’ 200 Clarendon Street in Boston holds the title of the city’s tallest building at 62 stories tall and 1.7 million square feet. Previously, the tallest building in the city was the Prudential Tower, a Class A+ building completed in 1962, at 52 stories tall and 1.2 million square feet. The city skyline has progressed significantly since pre-1928 building codes dictated a maximum height of 125 feet for commercial buildings, capping most buildings at six to 11 stories tall.

Boston boasts a long and illustrious history of innovation, including the country’s first public school, first subway system and first public park. JLL classifies Boston as an “Innovator” city in its 2018 “New World Cities” report; this classification of cities “possess high tech, innovation and research capabilities that make them important cities in the high-value economies.” Boston remains in the running to become home to Amazon’s coveted HQ2, a decision expected to be announced later this year.

Watch a 3D animation of the rise of downtown Boston over the decades and read about the evolution of the city’s skyline:

The Evolution of San Francisco

At 1,070 feet tall, the sweeping Salesforce Tower in San Francisco now holds the distinction of tallest office building west of the Mississippi River – a far cry from the four-story Montgomery Block, which held that title in 1853. The Salesforce Tower, developed by Boston Properties and Hines, reaches 61 stories and includes 1.4 million-square-feet of office space. The Salesforce Tower is expected to host tenants including CBRE, Accenture and WeWork upon completion this spring, in addition to 10,000 Salesforce employees.

A longtime base for shipping and manufacturing, San Francisco has been growing its tech employment with the number of high-tech jobs in the city tripled compared to a decade ago, according to CBRE research. Eight of the 10 largest leases in San Francisco in 2017 were by tech tenants, with Salesforce the city’s largest technology employer.

Watch downtown San Francisco change over the decades in a 3D animation and read about the evolution of the city’s skyline: