Meta note: This is not about a dome over a city, so this is not a duplication of those questions. Instead, this is about a building that is a dome in shape.
For precise reasons unbeknownst to outsiders, China has found an impressive expanse of solid bedrock, and has decided to build a massive dome. The dome has a few requirements:
- Provide as much protection against traditional (non-nuclear) means of attack as possible
The dome doesn't have to stop every assault, just offer meaningful protection as much as can hoped to be achieved.
- Be as large as possible in size
The government hopeful at including a few dozen city blocks inside this dome
- Act as a modern castle, supporting government functions and some civilian functions
The facility should act as a refuge for the government to retreat to, and allow it to bring some amount of infrastructure and supplies into.
- Provide a reserved, empty central region
They want the center of the dome to be as large as possible an empty area that can be later repurposed as needed. It should be free of any support beams, etc.
- Provide a means of sealing the facility off
There should be a means to provide an air-tight seal to the facility.
The government doesn't care about things like windows (who needs them?), and nor is it particularly concerned with any other issue of creature comfort. The people need to survive (for a short time, at least) when sealed in the facility but they don't need to be happy.
They want the facility constructed within 20 years. They have reached across the globe to architect firms to find the best minds to work on this project. The government discovered that the tallest buildings in the world (Burj Khalifa, Shanghai Tower, and Abraj Al Bait) cost \$1.5 billion, \$2.4 billion, and \$15 billion to make. They decided to set the budget at 10x this combined cost, \$190 billion. This will make it the single most expensive building constructed in modern times.
They feel like this budget will go a long ways since they have access to cheap labor and no egregious concerns about worker safety during construction.
When the architects asked if the government is willing to compromise on any of these points, they said that they were willing to compromise partially on any of the requirements, but not entirely on any.
Over a dinner meeting, one of the government officials sketched this design for a suggestion for the architects to look over.
How close to this dream can the Chinese government reach?