In-depth essays · #1 / 50 · Architecture, Consensus & Upgrades
Why Ethereum Chose the Rollup-Centric Roadmap Instead of Executing Everything on L1
Beyond the physical limits of a monolithic chain: how downtown L1 and satellite L2 districts divide labor
Early blockchain architects dreamed of a single giant mainnet executing every global payment and smart contract directly. Yet trying to achieve decentralization, security, and massive throughput on one layer inevitably pushes hardware requirements so high that only a handful of data centers can run nodes. Here is why Ethereum pivoted in 2020 toward a rollup-centric roadmap—and how that architectural split shapes the city you see today.
1. The Scalability Trilemma and Protecting the Home Verifier
For a single blockchain to execute tens of thousands of transactions per second directly, it must drastically enlarge blocks and shrink block times. Doing so causes state history to balloon by dozens of terabytes a year and demands server-grade hardware and enterprise bandwidth just to keep up. Ordinary citizens lose the ability to verify the ledger on consumer hardware, leaving validation to a few large institutions.
Ethereum’s foundational ethos is that anyone with a modest computer and consumer SSD should be able to verify the entire chain from home. Censorship resistance and credible neutrality depend on that low barrier. Rather than widening downtown avenues until home nodes break, Ethereum chose to make L1 the incorruptible supreme court and land registry of the ecosystem.
2. Outsourcing Execution While Concentrating Settlement and Data Availability
The rollup-centric roadmap separates a blockchain’s duties into three distinct jobs: executing transactions in order (Execution), publishing the raw transaction data so anyone can inspect it (Data Availability), and finalizing the resulting state root (Settlement and Consensus). The compute-heavy execution moves out to L2 districts, while downtown L1 stores the compressed batches and verifies proofs.
With this division of labor, users enjoy sub-second confirmations and sub-cent fees inside L2 districts while retaining an ironclad safety net: even if an L2 operator goes offline or acts maliciously, the underlying data recorded on L1 lets users prove and withdraw their balances directly on mainnet.
3. From Execution Shards to Data Shards (Proto-Danksharding and Beyond)
Early Ethereum 2.0 designs envisioned splitting mainnet into 64 execution shards that would each process transactions in parallel. As optimistic and zero-knowledge rollups matured faster than expected, researchers realized that giving rollups a massive, inexpensive data bulletin board was far cleaner than coordinating cross-shard execution inside the base protocol.
That realization produced EIP-4844 blobs in the March 2024 Dencun upgrade and the broader Danksharding roadmap. Instead of running thousands of retail storefronts inside downtown L1, Ethereum built a high-capacity freight terminal where dozens of L2 districts can post their compressed receipt bundles at minimal cost.
4. Seeing the Division of Labor Live in Ethereum City
Open the 3D view of Ethereum City and this architecture becomes tangible. Downtown Ethereum in the center hums along at a calm 15 to 25 transactions per second, yet its market cap and locked capital form the tallest skyline on the map. Meanwhile, the ring roads of surrounding L2 districts like Base, Arbitrum, and OP Mainnet teem with fast-moving vehicles.
Every orange blob truck and golden beam crossing the bridges between the districts and downtown represents thousands of L2 transactions being bundled and anchored into a 12-second Ethereum block—showing how one ecosystem pairs downtown trust with neighborhood speed.
Related districts in the city
Related glossary terms
This essay is an explainer written to help you read the city; it is not investment advice. Facts on this page are as of 2026-10 and may change. If you spot a mistake, please tell us through the contact page.