Example Sinatra app using the Namespace extension from Sinatra::Contrib

config.ru

require 'sinatra/base'
require 'sinatra/namespace'

class MyApp < Sinatra::Base
  register Sinatra::Namespace

  get '/' do
    'Home'
  end

  namespace '/blog' do
    get do
      'Blog'
    end

    get '/archives' do
      'Blog archives'
    end

    namespace '/categories' do
      get do
        'Blog post categories'
      end

      get '/web' do
        'Posts from “web” category'
      end
    end
  end
end

run MyApp